# Question
Title: Do chess engines store all of the previously analysed positions between moves
I am starting to play with chess engines. I notice that the best chess engines can take several minutes to move. I am wondering why. Before each move the engine examines all legal future moves to some depth. However it then seems to repeat this exercise for the next move. Given that the previous move was already included in the tree of moves examined, is this not inefficient ? Or have I misunderstood ?

\[Edit: I am assuming that the reason why move analyses are not cached is due to some memory limitations of the computer that just make it faster to restart the analysis\]

# Answer
> 21 votes
Programming chess engines is very complicated territory, so right up front I'll point you to the Chess Programming Wiki, which has a lot of great information on this topic.

## Background

Chess calculations (and many similar things) are generally modeled and thought of as "game trees" or "decision trees". Broadly, this tree is a directed graph, with one node at the top (the current position), leading to a node for each possible move, each of which leads to more nodes for each possible *next* move, and so on.

In their most simplistic, brute-force form, Chess engines generate all positions on this tree down to some depth limit ("ply"), evaluating each resulting position based on some complex criteria1. Then it plays the move that seems to lead to the best result. Nowadays, a lot of really complicated techniques have been developed to limit the number of positions that the engine has to look at, but I'm going to ignore those for the purpose of this answer, because they don't change the real issue at hand.

## Math Tangent

The basic reason that engines typically take about the same amount of time to consider each move is that the size of the decision tree increases exponentially with depth (`k`).

Consider the starting position. The top of the tree (`k=0`) is one node. There are twenty possible first moves for White, so there are twenty nodes at depth `k=1`. Then, Black also has twenty available moves for each of White's options: so at `k=2`, there are `20 * 20 = 400` possible positions! And it only gets worse as the players develop their pieces!

For example, let's pretend that there are always twenty possible moves for each player at any given time2. You instruct the computer to look ahead five moves for each player (ten ply). Let's look at the size of the brute-force tree at each level. For fun, we'll also look at the total number of positions in the tree (from the top to the given level).

```
Ply |    Positions   |  Total Tree Size
----------------------------------------
 0  | 1              | 1
 1  | 20             | 21
 2  | 400            | 421
 3  | 8000           | 8421
 4  | 160000         | 168421
 5  | 3200000        | 3368421
 6  | 64000000       | 67368421
 7  | 1280000000     | 1347368421
 8  | 25600000000    | 26947368421
 9  | 512000000000   | 538947368421
10  | 10240000000000 | 10778947368421

```

The result of each level being exponentially larger than the previous level is that the size of the whole tree is dominated by the *bottom level*. Consider the example above: the last level alone contains ten trillion nodes. The entire rest of the tree only contains five hundred billion. The tenth ply contains about 95% of the nodes in the entire tree (this is actually true at each level). In practice, what this means is that **all of the search time is spent evaluating the "last" move.**

## Answer

So how does this relate to your question? Well, let's say the computer is set to ten ply, as above, and further it "remembers" the results of its evaluations. It calculates a move, plays it, and then you make a move. Now two moves have been made, so it prunes all the positions from memory related to the moves that didn't happen, and is left with a tree that goes down the remaining eight moves that it already calculated: 26,947,368,421 positions!

All right! So we only need to calculate the last two ply! Using our 20-moves-at-each-depth estimate, the total number of moves we need to calculate here is still over ten trillion. The positions we already calculated only account for 2.5% of the possibilities! So even by caching last move's results, the best we can hope for is a 2.5% increase in speed! At heart, this is why even if your program caches previous results, you don't usually see a significant speedup between moves (excepting cases when the computer finds a forced mate or something, of course!).

---

## Simplification Disclaimer

There is *a lot* of complexity involved in this question, which is why I linked to the programming wiki at the very top and only attempted to explain the answer in broad mathematical terms. In reality, programs *do* generally cache parts of the tree from move to move, and there are other reasons why that's insufficient on its own--some simple reasons (e.g. a certain line might look good out to eight moves, but ends with a back-rank mate on move nine!) and many highly complicated ones (generally related to various clever pruning methods). So the computer must keep looking further ahead in an attempt to avoid making bad assumptions based on the previous move's cut-off depth.

---

1I'm not going to get into heuristic functions here, because that's its own incredibly complex area, but there are frequently some gains that can be achieved via position caching schemes here as well.

2An average branching factor of 20 is probably much too low.

# Answer
> 3 votes
**Example evidencing the memory of the engine:**

> Consider positions where deep theoretical novelties are discovered, in particular the game Caruana vs Topalov played this year. When you let the engine analyze the position after move 12 for a more or less short amount of time (say 10-15 minutes) you may check the suggested moves and see that the TN (`13.Re2!`) does not appear among them. Introduce the move yourself, go back a move and let the engine analyze again the same position for more or less the same time. Surprisingly, after some thought, now the engine does consider the TN among the best moves and approves it.

**EDIT: The original answer (kept below) is wrong, however, it provides a useful example of the memory of the engine, which has been quoted at the top.**

As far as I know, they do not, that is, they start the tree search almost from scratch at every move.

However, they must have some kind of function that actualizes the values for each move, and this function surely has some short-term memory. Some examples are positions where deep theoretical novelties are discovered, in particular the game Caruana vs Topalov played this year. When you let the engine analyze the position after move 12 for a more or less short amount of time (say 10-15 minutes) you may check the suggested moves and see that the TN (`13.Re2!`) does not appear among them. Introduce the move yourself, go back a move and let the engine analyze again the same position for more or less the same time. Surprisingly, after some thought, now the engine does consider the TN among the best moves and approves it.

I'm no expert on chess software, but this happens. This can be at least partially explained if (as said) the function that evaluates the moves for the position has some memory.

# Answer
> 3 votes
A typical chess engine will store some of the positions and their bracketing alpha-beta scores in a *transposition table* that can be consulted during subsequent searches. This table isn't consulted directly to choose the next move, but it makes searching for that move more efficient in two ways.

1. A position will likely be encountered multiple times in a search tree, being reached by a transposition or permutation of a sequence of moves. Because the table can be consulted such a position may only need to be evaluated few times (for different fixed search depths) instead of dozens of times as the position is visited and revisited.
2. A standard technique for alpha-beta searches is to use *iterative deepening*, repeatedly probing the tree at a greater search depth until the terminal depth is reached. The valuation scores computed in earlier iterations are used to order the moves searched in later iterations. Alpha-beta is known to perform better (i.e. prune more of the search tree) if good moves are searched before bad moves.

# Answer
> 2 votes
Henry Keiter already gave you a general answer, I'll give you a more technical answer. It's all about transposition table, search depth and cutoff. The discussion here is MUCH more technical than other answers, but it'll be beneficial to whoever wants to learn chess programming.

It's a common misunderstanding that if a position was evaluated before, the evaluation score could be reused as long as there is enough memory to store the moves. Chess programming is more complicated than that. Even given infinite memory, you'd still have to search the positions again. For each move, an evaluation score is attached with its deep and its bound. For instance, if the engine stores a move by fail-high, the table entry would have a lower bound. This means, if you're looking for a position you'd still have to check the bounds whether you can use the previous evaluation score.

Apart from that, each evaluation has a depth attached to it. In an iterative-deepening framework, as you increase the depth for each iteration, you'd still have to search those positions that you have searched already in the previous iteration.

The short answer to your question is that **an engine does store all of the previous analyzed positions (as long as enough memory), but those stored results can't be reused as easily as you might have thought**. In an opening phase where there are less repetitions, those stored results are most useful for move-ordering and a dozen of move-reduction heuristics. For example, one would assume the best move from the last depth be the best move in the current depth, so we'd sort the move lists and search the best move before any other moves. Hopefully, we'd get an early fail-high cutoff.

We don't have infinite memory for storing the positions. We'd need to define a hashing algorithm. Zobrist hashing algorithm give us a pseudo-random distribution, but sooner or later we'd still have to replace some existing entries.

# Answer
> 0 votes
Each engine has its own time management scheme. Some engines and GUIs let you set the pace at which the engine will play. Engines always calculate/evaluate/minimax as much as they can given the constraints imposed by the time management subroutines or the user settings. If an engine thinks for a long time, it is likely because the time control for the game is a slow one, or the user has set it to play slowly.

Positions and evaluations that the engine has calculated are stored in a hash table. The user can set the size of the available hash in the settings of most UCI engines. The engine itself uses a certain amount of RAM, and if you set your hash table size too high, the computer will start storing hash on your hard-drive in the form of virtual RAM. Hard drive memory is accessed slower than RAM, and you will usually be able to hear the hard drive churning away. A lot of users set the hash table size so that it will fit within the available RAM.

A large proportion of any hash table becomes useless after the engine and its opponent have made their moves as the other positions considered are no longer relevant. The engine will re-use the evaluations stored in hash, but some of the evaluations prove incorrect due to horizon effects once the engine goes deeper down the same line, so it often has to re-order its candidate moves.

Since the amount of hash is finite, an engine also has to make decisions as to what information to delete from its hash as it adds new information. The engine does not know in advance what moves will be played, so it may inadvertently delete information that would have been useful as it adds new data.

Engines in general do not examine all legal moves to a certain depth. They eliminate certain branches of the tree from consideration based on forward and backward pruning. Also, if a leaf-node position has captures or checks yet to be made, the engine will continue down that line until it reaches a quiet (quiescent) position. The actual tree is probably quite deep in some places, while other lines may have been truncated after a small number of moves.

---
Tags: engines
---


# Question
Title: What Chess Software allows creating a chess Ebook?
I would like to take an annotated pgn file, and convert it into an ebook I could conveniently read on amazon kindle (or its pc version), or android/Ios device. It might have to create diagrams where needed and make the book easy to go through without an extra chessboard. It would be good if the output format allowed to upload it to amazon store as well. Does such software/tool exist?

# Answer
You can export to html/web with most if not all of the major chess database programs (Chessbase, Chess Assistant, SCID). The problem is compiling the html pages into pdf/epub, as the formatting is usually not well-preserved for such conversions, but the book should remain readable with the diagrams. The converters are widely-available however, like Calibre (although I have not used that to convert ebooks specifically, but for managing my book collection)
> 4 votes

# Answer
This may or may not be your cup of tea, but if you are a LaTeX user, then SCID's LaTeX export feature produces ready-to-compile LaTeX source that yields rather nice (IMO) PDFs quickly and painlessly. There are a few options regarding how/whether comments and variations are to be displayed, and diagrams are automatically included wherever you have inserted a diagram NAG `D` into the game score (which can be inserted the same way that move annotations like `!?` are when using SCID). Here's a cropped screen grab from the PDF output of a fake sample game:
> 15 votes

# Answer
The Chessbase 12 and 13 manuals say that they can export games in epub or mobi format, but you would need to go through the game, and insert the diagram symbols first.

You can read pgn files as is on iOS/Android. For iOS, Giordano Vicoli's Chess Studio Light and Chess\_Studio can read, and play through annotated pgn files. On Android, Chess PGN Master Pro can read and play through annotated pgn files. Everyman chess sells pgn versions of its books through its iOS/Android Chess Viewer apps.
> 0 votes

---
Tags: software
---


# Question
Title: Is there chess software to play against that rates your skill through actual games?
Is there chess software out there that will try and rate your play? I vaguely recall an old Chessmaster software that did something similar, though by having you play through puzzles. I was looking for an actual engine to face you and gauge an estimated Elo rating somehow.

# Answer
> 6 votes
I realize what I'm about to suggest isn't exactly what you have in mind, but still, it is technically software, and it rates your skill through actual games: play games online against other people, e.g. at FICS, Playchess, ICC or chess.com.

Instead of using some software that would have you play games against an engine (perhaps with various "levels" that are *supposed to* reflect various Elo levels), and then has some algorithm or other that tries to convert your results against it into your own estimated real-world rating, my suggestion cuts out the middleman and throws you right into a real-world pool. This way seems more efficient if nothing else (and probably more fun).

Now any rating you get at one of the sites I mentioned will be on a somewhat different scale than that for, say, actual FIDE ratings, and they will differ from site to site as well. But you will usually have some way to translate your rating there into a percentile (within that site's playing pool), and that would give you better information about your playing strength than any purely algorithmic guess about it will.

# Answer
> 2 votes
Lucas Chess is free, and gives you a choice of playing for a "Lucas Elo" starting at 0 or a "Tourney Elo" starting at 1600. The program tracks your progress based on your games.

The full Shredder versions that run on Windows, iOS and Android all give you an Elo rating based on your performance against the engine in the last 10 games. The engine starts playing at a fairly low level, and if you have auto-strength adjustment switched on, it will raise the engine's level until you are each winning about half the games. (Apart from the Shredder version on the shredderchess web site, there is a version by Chessbase, but that one doesn't track Elo ratings).

The full versions of Remi Coulon's The Chess Crazy Bishop for iOS and Android also keep track of a rating for you I believe.

Shredder's ratings seem a bit high, and Lucaschess' and Crazy Bishop's a bit low, but anyway, they have that feature.

---
Tags: software, rating
---


# Question
Title: What software can I use to self-assess my own Elo rating?
What software (preferably free) can I use to do a self assessment to determine my own Elo rating?

# Answer
> 5 votes
Googling "Elo chess rating" provides a good answer, though it does not give any insight into what good answers are, or at least how that page is scoring answers:

* **Question 1:** blank=1000; f6,f3=2600; c5,d4=1900; c6,d4=1900; b4,c3=1400; c8,a6=1500; f6,g6=1400; e6,e5=1200; c8,d7=1600
* **Question 2:** blank=1000; g2,e4=2600; g5,h7=1950; h5,g6=1900; g2,f1=1400; g2,d5=1200; f2,f4=1400
* **Question 3:** blank=1000; c5,c6=2500; g3,g6=2000; e4,e5=1900; g3,g5=1700; e4,d4=1200; d6,e5=1200
* **Question 4:** blank=1000; e5,e6=2500; b3,f7=1600; b3,c2=1700; b3,d1=1800
* **Question 5:** blank=1000; e3,c5=2500; f5,h6=2100; e3,h6=1900; f5,g7=1500; f2,g3=1750; c8,f8=1200; f2,h4=1200; e3,b6=1750; e2,c4=1400
* **Question 6:** blank=1000; g5,f6=2500; c3,d5=1700; c4,b5=1900; f2,f4=1700; a2,a3=1200; e1,e3=1200
* **Question 7:** blank=1000; f6,h7=2500; f6,e4=1800; g6,g5=1700; a6,a5=1700; g8,h7=1500
* **Question 8:** blank=1000; b6,d8=2500; c8,e8=1600
* **Question 9:** blank=1000; e3,d4=2500; e4,g6=1800; e4,h7=1800; e3,h6=1700; d7,b7=1400
* **Question 10:** blank=1000; d8,d7=2600; f6,e8=2000; h7,h5=1800; c5,d4=1600; c8,a6=1800; a7,a5=1800; f8,e8=1400; d6,d5=1500

**Note:** Given the scores available above, the highest possible score is 2530, and the lowest possible score given all correct, but worse possible answers, is 1460.

# Answer
> 5 votes
chesstempo.com's tactics/endgame problems (which give you a rating) are probably just as good an estimate as anything else. They might be a bit under or over, but all other assessments will suffer similarly.

Similarly, playing on any of the online services (fics/icc are probably closest to reality) will give you a rating. Those are typically a bit inflated compared to FIDE or USCF.

# Answer
> 0 votes
Lucas Chess gives you a choice between playing for a "Lucas Elo" starting at 0 or a "Tourney Elo" starting at 1600. It includes 40 odd engines which have been handicapped or are rated between 600-3000, so you can find opponents near your level.

You could download the Shredder Classic 4 demo from the Shredderchess web site, and use it for free for one month. The Shredder Classic engine is weaker than the real Shredder, but the interface tracks your rating I believe.

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Tags: software, fide, rating
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# Question
Title: What is the difference between an inaccuracy, a mistake and a blunder on lichess?
I used lichess to analyse some of my games (lichess.org -\> tools -\> import game). It puts my bad moves (and those of my opponent) in one of three categories; "inaccuracy", "mistake" and "blunder". I guessed from the names (and the positions) that an inaccuracy is better than a blunder, but I wondered what the definitions were.

# Answer
> 13 votes
Blunder: 300 centipawns

Mistake: 100 centipawns

Inaccuracy: 50 centipawns

This is sourced from http://en.lichess.org/qa/75/how-are-these-determined-blunder-mistake-and-inaccuracy

It is the first thing that appears when you google "lichess inaccuracy mistake blunder".

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Tags: analysis, engines, blunder
---


# Question
Title: Is it true that Queen's Gambit tends to have positional play and King's Gambit A tactical one?
I have heard somewhere that Queen's Gambit is favored by those who like quiet positional play and King's Gambit by those who like lively game studded with tactical traps. Is this true?

# Answer
It depends a little. The Queen's Gambit can lead to very lively play, if both parties are willing, but it's easier to turn it positional, as the Queen's Gambit is more of a "pseudo-gambit" than the King's Gambit; White will almost always be able to regain his pawn if it's taken, even without going all out for blood.

The King's Gambit is different. White opens up lines in front of his own king, and in order not to get into a worse position, White will have to play very energetically, as it's more difficult to regain the lost pawn. If White loses his initiative without regaining his sacrificed pawn, things can turn very ugly.

So it's more a matter of White being forced to be prepared to play that way in the King's Gambit, as opposed to the Queen's gambit, as White in the latter opening doesn't need to worry as much about being worse if his attack doesn't go through.
> 6 votes

---
Tags: tactics, positional-play, queens-gambit, kings-gambit
---


# Question
Title: Could black have saved the rook-endgame?
```
[Event "FIDE Women's World Chess Championship"]
[Site "Sochi RUS"]
[Date "2015.03.27"]
[Round "4.2"]
[White "Dronavalli Harika"]
[Black "Meri Arabidze"]
[Result "1-0"]
[ECO "D03"]
[WhiteElo "2492"]
[BlackElo "2374"]
[PlyCount "189"]
[EventDate "2015.03.17"]
[FEN ""]
[StartPly "46"]

1. d4 Nf6 2. Nf3 e6 3. Bg5 c5 4. e3 d5 5. Nbd2 Be7 6. c3 Nbd7 7. Bd3 b6 8. O-O
Bb7 9. Ne5 Nxe5 10. dxe5 Nd7 11. Bxe7 Qxe7 12. f4 O-O 13. Qh5 f5 14. exf6 Nxf6
15. Qg5 Rae8 16. Nf3 Nd7 17. Bb5 Qxg5 18. Nxg5 Bc8 19. Rad1 Re7 20. Bxd7 Bxd7
21. Nf3 Be8 22. Ne5 Bg6 23. Nxg6 hxg6 24. g3 Rd8 25. Rd2 e5 26. Rfd1 exf4 27.
exf4 Red7 28. Kf2 Kf7 29. Kf3 Kf6 30. h4 Rd6 31. Rd3 R8d7 32. Kg4 Rd8 33. Re1
d4 34. cxd4 cxd4 35. Kf3 Kf7 36. Re5 Rc8 37. Re4 Rcd8 38. b3 R8d7 39. a4 Rd5
40. b4 a6 41. g4 Rd8 42. Re5 R5d6 43. Ke4 R8d7 44. f5 gxf5+ 45. Rxf5+ Kg8 46.
h5 Kh7 47. Rg5 Kh6 48. Kf4 Kh7 49. Re5 g6 50. Ke4 Kg7 51. Rg5 Re7+ 52. Kf4 a5
53. bxa5 bxa5 54. Rxg6+ Rxg6 55. hxg6 Rd7 56. Ke5 Kxg6 57. Rxd4 Rb7 58. Kd5 Kg5
59. Kc5 Kh4 60. Rc4 Rb8 61. Kd5 Rb7 62. Rc5 Rb4 63. Rc4 Rb8 64. Ke5 Kg5 65. Rc5
Rb4 66. Rxa5 Rxg4 67. Ra6 Kh5 68. a5 Rg5+ 69. Kd4 Rg4+ 70. Kc5 Rg5+ 71. Kb6
Rg6+ 72. Kb7 Rg7+ 73. Kc8 Rg5 74. Kd7 Rg7+ 75. Ke8 Rg5 76. Kf7 Rc5 77. Kg7 Rc7+
78. Kf6 Rc5 79. Ra8 Kh4 80. a6 Rc6+ 81. Kf5 Rc5+ 82. Kf4 Rc4+ 83. Ke3 Rc7 84.
Rb8 Kg5 85. Rb7 Rc4 86. Kd3 Ra4 87. Rb6 Kf5 88. Kc3 Ke5 89. Kb3 Ra1 90. Kc4 Ra2
91. Rh6 Ra1 92. Kc5 Ra2 93. Kb6 Rb2+ 94. Kc7 Ra2 95. Kb7 1-0

```

62...Kg4 was not enough to draw and white could win with 63.Ra5. After 66.Ra5, the position was theoretically drawn. Black slipped with 73 ...Rg5 ? and White slipped with 74.Kd7 ? (Correct moves were 73...Rg8 and 74.Ra8) . Finally, black slipped with 77...Rc7 and white did not allow a drawn position anymore.

Beginning with the double-rook ending, could black hold the position, or where did Black make the decisive error?

# Answer
Black's 34 ...cxd4 is probably a bad choice. Taking with the rook seems good if also they could have exchanged a pair of rooks, because the pawn is blocked by the white rook. Also Black's doubled pawns on the g-file from move 24 to 43 gives an advantage to white. So i think black couldn't have saved the game unless White blundered.
> 1 votes

# Answer
On my analysis, with Stockfish 6, yes the losing misstep was failing to use the forcing move 52...Rf6+ to keep the white king back. Active kings are decisive in otherwise equal endgames. Once that white king got to e5, the game was (technically) decided, and 52...Rf6+ was the best chance to prevent that. The only other way was to try 55...Kxg6 56.Rxd4, which just barely possibly might be a technical draw; my opinion is not, but we'll have to wait for 7-piece tablebases to prove it one way or the other.

Up until 52...a5 black was completely holding the draw.
> -1 votes

---
Tags: analysis, endgame, blunder, rook-endgame
---


title: Confusion about Touch and move rule

text:
# Question
Title: Confusion about Touch and move rule
I accidentally touched my bishop and opponent's "Knight", while reaching for my queen during a game, almost simultaneously. Am I forced to take the opponent's piece?

# Answer
> 5 votes
FIDE Article 4.3:

> Except as provided in Article 4.2, if the player having the move touches on the chessboard, with the **intention of moving or capturing**:
>
> a. one or more of his own pieces, he must move the first piece touched that can be moved
>
> b. one or more of his opponent’s pieces, he must capture the first piece touched that can be captured
>
> c. one piece of each colour, he must capture the opponent’s piece with his piece or, if this is illegal, move or capture the first piece touched that can be moved or captured. If it is unclear whether the player’s own piece or his opponent’s was touched first, the player’s own piece shall be considered to have been touched before his opponent’s.

If a player touches a piece without the intention of moving or capturing (e.g. fingerslip), there is no touch move restriction.

# Answer
> -3 votes
No, as long as you say adjust your fine. It has to be deliberate movement in order for touch move to be called upon

---
Tags: rules, tournament
---


title: Examples of hidden gems

text:
# Question
Title: Examples of hidden gems
For the moment, I have a hard time finding time for chess due to studies, so for the time being, chess has to be a purely recreational activity for me. What I'm looking for are examples of beutiful games that may or may not be very well known.

For example, I like the following game played between Yuri S. Gusev (white) and Yuri Averbakh(or E. Auerbach, depending on the source) in 1946. In the game, White's winning idea could be described as(just slightly bending the truth):

* Give your opponent a rook
* Afterwards, give your opponent a queen, to balance things out
* After that, dominate your opponent, and win

The game:

```
[Date "1946"]
[White "Gusev, Yuri"]
[Black "Averbakh, Yuri or Auerbach, E."]
[Result "1-0"]

[FEN "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w - - 0 1"]

1. e4 c5 2. Nf3 d6 3. d4 cxd4 4. Nxd4 Nf6 5. Nc3 g6 6. Be2 Nc6 7. Nb3 Bg7 8. O-O Be6 9. f4 Rc8 10. f5 Bd7 11. g4 Ne5 12. g5 Ng8 13. Nd5 f6 14. Be3 b6 15. Nd4 Kf7 16. c3 Qe8 17. Ne6 Bxe6 18. fxe6 Kf8 19. Nxf6 Nxf6 20. gxf6 Bxf6 21. Bh6 Kg8 22. Rxf6 exf6 23. Qxd6 Rc6 24. Qxe5 fxe5 25. Rf1 Rc8 26. Bd1 Rc4 27. Bb3 b5 28. Bxc4 bxc4 29. b3 a5 30. bxc4 Qe7 31. Kg2 Qa3 32. Rf2 Qe7 33. Rf1 g5 34. Rf5 g4 35. c5 Qd8 36. c6 Qe7 37. c7 1-0

```

The purpose behind this post is that I would like to generate a collection of nice and inspiring games on this site, which I haven't really found yet. I know that it's quite subjective to determine whether a game is beautiful or not, but I feel like stuff like this might bring something valuable to this community.

# Answer
Gusev - Averbach is a good start; it reminds me of the following game, where less material is sacrificed (only a knight) but more pieces are dominated:

# The immortal Zugzwang game

(taken from here)

```
[Date "1923"]
[White "Saemisch, Friedrich"]
[Black "Nimzowitsch, Aron"]
[Result "0-1"]

[FEN "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w - - 0 1"]

1. d4 {Notes by Nimzowitsch's "My System"} Nf6 2. c4 e6 3. Nf3 b6 4. g3 Bb7 5. Bg2 Be7 6. Nc3 O-O 7. O-O d5 8. Ne5 c6 {Safeguards the position} 9. cxd5 cxd5 10. Bf4 a6 {Protects the oupost station c4, i.e., by ...a6 and ...b5.} 11. Rc1 b5 12. Qb3 Nc6 {The ghost! With noiseless steps he presses on towards c4.} 13. Nxc6 {Samisch sacrifices two tempi (exchange of the tempo-eating Knight on e5 for the Knight which is almost undeveloped) merely to be rid of the ghost.} Bxc6 14. h3 Qd7 15. Kh2 Nh5 {I could have supplied him with as yet a second ghost by ...Qb7 and ...Knight-d7-b6-c4, but I wished to turn my attention to the King's side.} 16. Bd2 f5 {!} 17. Qd1 b4 {!} 18. Nb1 Bb5 19. Rg1 Bd6 20. e4 fxe4 {! This sacrifice, which has a quite surprising affect, is based upon the following sober calculation: two Pawns and the 7th rank and an enemy Queen's wing which cannot be disentangled - all this for only one piece!} 21. Qxh5 Rxf2 22. Qg5 Raf8 23. Kh1 R8f5 24. Qe3 Bd3 25. Rce1 h6 {!! A brilliant move which announces the Zugzwang. White has not a move left. If, e.g., Kh2 or g4, then R5f3. Black can now make waiting moves with his King, and White must, willy-nilly, eventually throw himself upon the sword.} 0-1

```
> 3 votes

# Answer
"Positional" Queen Sacs? Hidden Gems? Surely we must mention Mr Nezhmetdinov here!

```
[Event "Rostov"]
[Site "Rostov"]
[Date "1962.??.??"]
[EventDate "?"]
[Round "?"]
[Result "1-0"]
[White "Rashid Gibiatovich Nezhmetdinov"]
[Black "Oleg L Chernikov"]
[ECO "B35"]
[WhiteElo "?"]
[BlackElo "?"]
[PlyCount "65"]
[FEN ""]

1. e4 c5 2. Nf3 Nc6 3. d4 cxd4 4. Nxd4 g6 5. Nc3 Bg7 6. Be3
Nf6 7. Bc4 O-O 8. Bb3 Ng4 9. Qxg4 Nxd4 10. Qh4 Qa5 11. O-O Bf6
12. Qxf6 Ne2+ 13. Nxe2 exf6 14. Nc3 Re8 15. Nd5 Re6 16. Bd4
Kg7 17. Rad1 d6 18. Rd3 Bd7 19. Rf3 Bb5 20. Bc3 Qd8 21. Nxf6
Be2 22. Nxh7+ Kg8 23. Rh3 Re5 24. f4 Bxf1 25. Kxf1 Rc8 26. Bd4
b5 27. Ng5 Rc7 28. Bxf7+ Rxf7 29. Rh8+ Kxh8 30. Nxf7+ Kh7
31. Nxd8 Rxe4 32. Nc6 Rxf4+ 33. Ke2 1-0

```
> 2 votes

---
Tags: history, master-games
---


title: Rating based off play level?

text:
# Question
Title: Rating based off play level?
Is there a program that can tell your rating based off *how well* you play in the game? (NOT based on result). Thanks.

# Answer
> 6 votes
This is called Intrinsic Performance Rating.

There has been a Kaggle Competition in which the winner predicted the Elo on the basis of a single game with an average error of 150 points.

As far as I know there is no single piece of software that gives you these predictions, but the Kaggle Competition provides links to the code used by the participants.

---
Tags: software, rating
---


# Question
Title: Chess engine with an ELO of less than 1800
I am looking for an UCI compatible engine with an ELO of less than 1800. Not a version of Houdini or Stockfish with an ELO of 1800. I want a engine with a real ELO rating of 1800 or less. If you can help me with links, that would be great.

# Answer
Take a look at numpty. It claims to have a ELO of about 1500-1800. I've played it on FICS before and it usually has a blitz rating of 1900-2100. Note that FICS ratings are usually horribly skewed by all the cheating that happens on there.
> 2 votes

# Answer
Adam Hair has a rating list for weaker engines:

http://adamsccpages.blogspot.com/p/also-rans-rating-list.html

Grizzly and Chenard are UCI, but a lot of the weaker engines tend to be CECP.
> 2 votes

# Answer
Actually, on the CCRL 40/4 there're around 170 engines under 1800, not just a dozen. You can also check this list based on bullet games: http://e4e6.com/ratings.php?id=1001 Most of the engines work properly, especially at long time controls. Almost all of them are still available on the Internet, just Google them.

Alex
> 1 votes

# Answer
There is an engine called Delfi made by msb software. It is designed to play at lower ratings but also to play more like a human amateur. It is commercial, not free but I think there is a free version with some limitations.
> 1 votes

---
Tags: engines, software, rating, elo, uci
---


# Question
Title: Is there a site that provides (legal) online access to free chess books?
As the title says, is there a site that provides (legal) online access to free chess books?

# Answer
> 7 votes
Open Chess Books is a site that aims to “republish classic chess books, with all diagrams transformed in animated boards, and release them for free.”

They only have two books at the moment (*Modern Ideas in Chess* and *Chess Fundamentals*), but it's a great resource so far.

Predator at the Chessboard by Ward Farnsworth is a great primer on chess tactics that's available to read for free online or purchase in print form.

# Answer
> 3 votes
The Internet Archive is probably the largest repository of free ebooks. Project Gutenberg has old classics by Staunton, Bird, Ed Lasker and Capablanca.

---
Tags: learning, books, online
---


# Question
Title: What would approximately be the ICCF rating of a GM with no external help and of a computer with no human judgment?
I need some players who play at the ICCF (International Correspondence Chess Federation) to answer this question.

What would approximately be the ICCF Elo rating of the two following players?

* Player A is a Grandmaster with an OTB rating of 2500 Elo FIDE. He will not use any engine, nor will he use any opening database, nor will he use any opening book, nor will he use any endgame tablebase, nor will he use any form of outside assistance. He will play using only his brain. He will use on average about 5 minutes per move, which also happens to be the average time per move of humans in OTB chess at classical time control. Player A is 100% human.
* Player B is in reality a patzer, with an OTB rating of 1200 Elo FIDE. For the opening he will use an opening database and in each position he will just pick one of the popular moves which score well. For the rest of the game, he will use one (and only one) of the top 3 best engines: Komodo 9, Stockfish 6 or Houdini 4 (64-bit version). His engine will have 7-men endgame tablebases. At each position he will let his engine run for one hour (using 4 CPUs) and then he will blindly pick his engine’s first suggestion. He will not offer draws or accept draws early, he will continue his games until it is very clear that the position is a draw. He won’t resign early either, he will wait until he gets checkmated. Player B is 100% computer.

Note that I only need an approximation. But still, try to make your approximation as accurate as possible.

# Answer
> 6 votes
I play on ICCF. My guess is that the engineless GM might be able to maintain a 2000 rating by beating other engineless players or players who are bad at engine use.

I don't think the second player would do that well actually. Players in the 2300+ range are all using anti-engine strategies, following GM opening theory, have their novelties, so they can lure him into opening traps or positions his engine has trouble evaluating. I would guess he'd wouldn't go much beyond 2100. I've played against 2200 players who are pure engine once out of book, but they put more effort into their openings than your player B does.

There is another breed of player you haven't mentioned: the engine monkey master. These are players with 2000+ ratings over the board. They could potentially try to carry out strategic plans in the middlegame, but they get so caught up in the engine analysis they end up play positionally suspect moves. They do contribute a lot to the openings and endings though, so you see them in the 2300-2400 range.

# Answer
> 1 votes
Player A will have difficulties to achieve 2000-2100. Player B has something like 2400 guaranteed, but he will need to play many games to achieve that rating. Player A can start with his FIDE rating, but he will go down without any computer help.

---
Tags: engines, rating, elo, correspondence-chess, computer-chess
---


title: What's with ChessBase and WB engines?

text:
# Question
Title: What's with ChessBase and WB engines?
I've been using ARENA for quite a while(5 years to be specific) and I have a collection of Winboard engines that I love. I recently parted with $140 to buy Fritz 14. But to my dismay it doesn't support Winboard engines. This is a big disappointment considering the cost of the product. How can I get my favorite WB engines to play in the FRITZ GUI? Why doesn't ChessBase include native WB support with their products?

# Answer
> 4 votes
ChessBase products only support two protocols:

1) Their own proprietary (used by the .eng engines)

2) The UCI (used by by many commercial / open source engines)

You must see a "Create UCI Engine" option in either Fritz or ChessBase (I used it all the time to make tournaments between engines).

I also use Arena for engine tournaments and supports both UCI / Winboard. You should be able to use UCI engines in both Arena / ChessBase.

Some notes:

* There are adapters for Winboard to UCI like Good UCI to WinBoard adapter (but I don't have seen the opposite).
* I have learned that whenever I have to buy a commercial engine (like Houdini or Komodo) I prefer to not buy it thru ChessBase (because they only provide the .eng and only works in their own interface).

# Answer
> 0 votes
ChessBase products Fritz 5.32 and 6 and Junior 6 and 7 had support for Winboard engines, but not UCI. In February 2002, ChessBase announced that they were switching and would only support UCI and not Winboard. Stefan Meyer-Kahlan released the UCI protocols in 2000, and ChessBase decided to add Shredder to their roster of engines, so that's probably why they went with UCI.

Odd Gunnar Malin made a WB2UCI adapter that probably still works. You can download it here:

https://www.mediafire.com/?1laijk2jhpod1g8

You change the name of the wb2uci.exe to whatever the winboard engine is, open the wb2uci.eng file and point to the actual winboard engine, and add any parameters you want. Then install the renamed wb2uci.exe file in Fritz or ChessBase as if it were a UCI engine.

---
Tags: chessbase
---


# Question
Title: Chessbase 13 How to install UCI Engine when menu item is missing?
I have the latest version of Chessbase 13, I have bought a license and activated it online. For some reason, when I open a new board and go to the `Home` tab I do not have the menu item `Create UIC Engine` button.

As you see I have the choices `Default Kibitzer`, `Add Kibitzer` and `Remove Kibitzer`, but no additional choices while the image in the manual shows there is a small button below `Remove Kibitzer` that opens additional choices.

Have anyone else experienced this? I have emailed Chessbase support, but they have not seen this before.

# Answer
> 4 votes
At the end of the line Remove Kibitzer, there is "UCI" written in red. Click on that.

# Answer
> 1 votes
It is the size of the window that matters. Make it smaller and they will become available (I assume the same is tru for making it larger, but I can't verify as this was my max screen size).

---
Tags: chessbase, uci
---


title: How to use stockfish for ChessBase?

text:
# Question
Title: How to use stockfish for ChessBase?
I have downloaded Stockfish 6 and also I have ChessBase 13 64-bit. I have unzipped to Stockfish how do I combine the two so I can use Stockfish?

# Answer
> 2 votes
Open a game window. On the File ribbon, look for a little UCI written in red just after where it says Remove Kibitzer. Click on that, then in the dialog that pops up click on the button with three dots, and navigate to wherever you have Stockfish on your system. The Author and Name will get filled in automatically. Click on OK, and now Stockfish will appear in the dialog that appears when you click Add Kibitzer.

---
Tags: stockfish, chessbase
---


title: Confused about ChessBase

text:
# Question
Title: Confused about ChessBase
I'm really confused about the differences between the products that ChessBase offers. For example, on the website, Deep Fritz is said to be an engine. But after a bit of research, it turned out that it holds a database, a multimedia directory, a playchess.com client, and a tactics trainer! ChessBase is only said to be a database although it also features training courses. Also, ChessBase markets Houdini which is said to be "the world's strongest engine". So, if it is, doesn't that make Deep Fritz rubbish ? Please clear my confusions.

# Answer
Houdini is a chess engine written by an external developer. It is not a user interface that you can visually interact. This is where the confusion: when ChessBase mentions Houdini, they actually mean *running* the Houdini chess engine on their ChessBase user-interface. If you search on Wikipedia, Houdini is simply a chess engine and has nothing to do with ChessBase. ChessBase does that because they want to sell their user-interface bundled with a strong chess engine.

Similarly, Deep Fritz is a chess engine just like what Houdini is. Again, what they really mean is *running* the Deep Fritz chess engine on their ChessBase graphical user interface.

```
ChessBase = user-interface written by the ChessBase company
Deep Fritz = the ChessBase user-interface bundled with the Deep-Fritz chess engine
Houdini = the ChessBase user-interface bundled with the Houdini chess engine

```
> 1 votes

# Answer
Just adding a few details to Student T's answer:

**Fritz** denotes a *chess engine* as well as an *(graphical user) interface*. The reason for this is a historical one. Back in the times, almost all commercial chess engines would bring their own interfaces (Fritz, ChessAssistant, Shredder, Rebel, ...) - and a lot more stuff like databases. The hegemony of those commercial programs in the mass market was largely unbroken until maybe three or four years ago. After this, everything goes blurry and messy (Rybka, Stockfish, xfce, EGTBs, Online Chess, scidb, ...). But back to the point.

The distinction between engine and interface only emerged after the terms "Fritz" and "Shredder" were coined. There is a third term which is the *database application*. It can organise collections (databases) of games efficiently. To add to the confusion, **ChessBase** the company named their database product - you guessed it - *ChessBase*.

* If you buy Deep Fritz today, you get the engine and the interface and some extra stuff (but only a rudimentary database interface).
* If you buy ChessBase, you get the database interface (and probably databases and a player base), but no engines.
* All sorts of free strong UCI engines have emerged on the internet (some outperforming Fritz). You could use a free *interface* like Arena and a free *engine* like Stockfish and you probably wouldn't fare noticeably worse than with a $100 software bundle.
> 2 votes

# Answer
Deep Fritz 14, Houdini 4, Komodo 9 and Rybka 4 all use the same Graphic User Interface (GUI). It allows you to blundercheck, do full game analysis, calculate elo ratings for sets of games. It has a Handicap and Fun mode for dumbing down these engines, so you have a chance. You can also play timed games, and adjust the engine's style. There is also a hotness meter that shows you how sharp or dynamic the position is.

ChessBase 13 cannot do timed games or full game analysis, but it can do infinite analysis. It can create opening and endgame theme keys, and has a search mask for locating games with certain traits quickly. Lists of games can be sorted by player name, year, result, elo rating, tournament just by clicking on the header.

Komodo 9 is probably stronger than Houdini 4 which is stronger than Rybka 4 which is stronger than Deep Fritz 14. Some people like the slightly weaker engines because they believe they have special characteristics, for example a sharp or solid style, more human feel, or the like.

Both ChessBase and the engine GUIs allow you to annotate games, add variations, draw arrows on the board, watch videos, do infinite analysis, play on Playchess. The Engine GUIs have some basic database functions. The Engine GUIs are mainly for playing against, and ChessBase is for building an opening repertoire, and preparing to play specific opponents.
> 2 votes

---
Tags: chessbase, houdini, fritz
---


# Question
Title: Is there ant database that will return the reversed position?
I recently started an online game as White that began as follows.

```
[FEN "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1"]
1. Nf3 f5  2. d3 Nc6  3. e4 e5

```

Here I deliberately decided to lose a tempo with 4. d4 and transpose into a Vienna reversed with the Black pieces. I knew what I was doing and therefore was able to avail myself of various resources (books/databases) on the Vienna game, but this got me to wondering. Are there any databases against which you can enter a position, and it will also look for the reversed position?

# Answer
Chessbase opening trees (ctg) detect white/black transpositions. My database has 59 games starting 1.e3, 9 games where black answered 1...e5, but then 28000+ games for 2.e4.
> 4 votes

# Answer
http://chessok.com/?page\_id=352 I've been using this for my correspondence games at chess.com, hope this helps you.
> 3 votes

# Answer
Not to my knowledge. Although, a simple solution would be to manually input the moves with sides reversed.
> 2 votes

---
Tags: database, software
---


# Question
Title: Since each engine has its own style of play… which engines are more positional/strategic and which engines are more sharp/tactical?
I’ve heard that each engine has its own style of play. Some are more positional and strategic, while others are more sharp and tactical.

And so my question is: could you roughly sort the following engines from the most sharp and tactical to the most positional and strategic?:

* Critter 1.6a
* Deep Fritz 14
* Gull 3
* Hiarcs 14
* Houdini 4
* Komodo 7a
* Rybka 4
* Stockfish 5

And does the style of an engine depend on the time it takes to get to a high depth? I was thinking that maybe, for engines of roughly the same strength, engines that quickly get to a very high depth are more sharp and tactical, while engines that do not quickly get to a high depth have a richer and more complex evaluation function and therefore they are maybe more positional and strategic.

# Answer
**EDIT:** With the advent of Lc0 and the new Stockfish 13, unfortunately this question is now beyond human comprehension.

I am not very well versed on the theory of chess computer programs, but I've used them for a long time. At first, I used **Houdini**, then switched for a few months to **Rybka**, back to Houdini, had another short incursion into **Komodo**, back to Houdini and now I've been using **Stockfish** for a year or so. The following is based on my personal feelings with the aforementioned engines (and thus, subjective).

1. **Rybka**: It is the model of a tactical player. Playing on (very) low depth, some times deviates from the opening theory just to see if the opponent would fall into a well-hidden trap. Playing on normal depth, it takes a little to make his mind, but he finally chooses (usually) a theoretical line. It also relies strongly on tricks and tactics to avoid calming the position (although not always with success). When in a closed position, this engine collapses.
2. **Komodo**: It plays half-positional, half-tactical. That is, he has no preference over either, but has good calculating power and can play relatively good in semi-closed positions. His endgame skills, however, are what differentiate him from other engines. There he is hard to beat when in an inferior position and plays accurately when having a small advantage.
3. **Houdini**: This is a good combination of tactical abilities and positional understanding. Can evaluate well (not great, but well) closed positions and two of his main characteristics are long combinations involving piece sacrifices to recover the piece and even win a couple of pawns after 10 to 15 moves and a tremendous defensive capability, being able to hold a draw in seemingly lost positions (it is said that this is where the name came from, in reference to his escapist abilities). Not extremely good at the endgame.
4. **Stockfish**: Extreme versatile engine, can calculate long and precise and has a good understanding of the positional nuances of a closed position. There are few positions in which he cannot perform well, and these can be easily tuned from the "options" available in any GUI (that is, change the way he always looks for a win or if he can allow a draw when having material advantage). However, I think it has a small tendency to drawish positions.
> 7 votes

# Answer
Someone on Talkchess did a test getting the top engines to play against each other in an opening which required an understanding of pawn breaks, such as the King's Indian or Stonewall. Houdini, Komodo, Rybka and Stockfish all struggled in these positions refusing to advance their pawns, and pursuing ephemeral tactical gains instead. At blitz time controls, engines overestimate the value of space and refuse to play obvious freeing moves.

Another area where engines fall down is planning for the endgame. Human grandmasters aim for certain positions which are known to be theoretically won or drawn, but engines are always caught up in short term goals, and quite willingly enter positions that are lost strategically. I think that it was Larry Kaufman who said that top engines' evaluation functions at around a 2300 or 2400 Elo level, but they never makes tactical mistakes.

Both Kasparov and Anand have commented on Hiarcs' positional understanding being more notable than other engines. Tord Romstad, one of the authors of Stockfish, acknowledged this in a fairly recent comment when he noted that on slow hardware, Hiarcs plays surprisingly well suggesting its strength lies more in its evaluation. Hiarcs has an elaborate evaluation schema, but the top engines tend to rely on a fast search.

Some engines are noted for playing in a sharp style: Tao, TheKing Tribute, Thinker and Zappa Mexico Dissident Aggressor. Some engines have parameters for sacrifices or king attack or their contempt works this way: Amyan, Fritz 10, Gambit Tiger, Junior 7 and Rybka Dynamic.
> 1 votes

---
Tags: engines, software, positional-play, stockfish, houdini
---


title: Playing Styles of Fischer and Botvinnik

text:
# Question
Title: Playing Styles of Fischer and Botvinnik
They say Botvinnik had 'scientific' approach to chess and Fischer's style was crystal-clear.

What does it mean?

Could you please enunciate about the styles of these masters in a more lucid way?

# Answer
> 8 votes
Botvinnik believed in peer review. He would write up annotations for his games, and publish them hoping for feedback from other players. He also recommended to his students that they annotate their losses, and also look for mistakes in the games they won. These elements are all part of his 'scientific' approach.

Fischer always kept the endgame in mind, preferred bishops over knights, grabbed pawns if he thought he could get away with it. Mikhail Tal would wait until the time control drew near, and then suddenly start to complicate the position, trying to induce his opponent into blundering. Fischer was much more straightforward, playing the board more than the man, not indulging in psychological ploys as much (at the board anyway). After the game was over, his opponent would look at Fischer's moves, and think they looked obvious in retrospect. These are the factors that make his style 'crystal clear.'

# Answer
> 3 votes
I wouldn't read too much into these descriptions. We like to make up adjectives to describe great people all the time - these are not always rooted in any kind of quantifiable fact. It is not likely that you would become as good as Botvinnik by "copying his style", if that even means something more than "play the same openings".

Having said that, I believe that Botvinnik was, in addition to a great chess player, also a great computer scientist. He was one of the pioneers in using computers to analyze chess positions - hence a possible clue as to where the "scientific" angle comes from. I doubt that his chess ability was somehow contingent on this work - I think he would have been a great chess player even if he was an accountant or historian.

As for "crystal-clear", that sounds to me like the typical thing you would say if you are looking to praise a man of great skill without committing yourself to what you are actually saying. I mean, it's not like you can somehow *disprove* it.

---
Tags: fischer, style, botvinnik
---


title: The most honourable way to lose?

text:
# Question
Title: The most honourable way to lose?
When in a bad position, is it more honourable to resign or to face defeat? And if it is to face defeat then is there a time when resigning is considered an honourable thing to do, or is it always considered the cowards way out?

# Answer
Playing on in a hopeless position when it is clear to you that your opponent has the knowledge, skill and time to finish you off is never honourable. It shows a lack of respect.

If you have played your moves much faster than your opponent so that he is in serious time trouble and you aren't, then it is perfectly reasonable to play on. With just a few seconds left playing without increment he may not have enough time to deliver the coup de grace.

In the reverse situation where you are the one with very little time on the clock it is excusable but perhaps not particularly honourable to play on as you can always claim that with so little time to think the hopelessness of your position hadn't sunk in.

Note that positions where you have very few moves and so stalemate is a possibility are not hopeless. Nor are positions where, although material down and so expected to lose with best play, you have some prospects of counterplay in a double-edged position.
> 2 votes

# Answer
It depends. When you are completely lost, and there is nothing interesting, you should resign. I say "nothing interesting" because it is etiquette to let your opponent mate you if he has a pretty force mate against you.
> 1 votes

---
Tags: losing, resigning
---


title: SCID (or any alternative) on iPad

text:
# Question
Title: SCID (or any alternative) on iPad
I'm looking for a Scid port (or alternative software) to run on an iPad. Currently I use SCID + Stockfish in my Ubuntu Linux, but I'd like to use my iPad for the same functionality.

AFAIK there's a SCID port for Mac, but I've found nothing for the iPad. Any suggerence?

Update:

When I ask for the "same functionality" what I'd like most would be:

* Games database (of course).
* Database search.
* Openings explorer (aka tree view).
* Analyze games.
* Annotate games.

Others like playing on FICS/ICC or playing the computer are not needed as I can use other clients for that.

# Answer
> 7 votes
Giordano Vicoli's Chess\_Studio (not to be confused with a similarly named e-reader app from Gambit Publications) seems to have many of the features you are looking for. I've only tried Chess Studio Light, but it is able to import a much wider range of PGN files than any of the PGN viewer apps. Within a PGN archive, you can view lists of games sorted by Event, Opening, Player or Year. The game window in the Lite version allows you to add nested variations and text and some NAGs (!, ?, only move, and novelty), but you may need the paid version to analyze with Stockfish as kibitzer, or add long lines of moves to a game. You can save games, or send them by email. It registers itself as a PGN program, so you can use the "Open in..." menu item to add PGN files to it from programs which have "Open in..." You can download and upload from Dropbox and iCloud. You can download from TWIC or PGN Mentor. It also has Nalimov tablebases for 6 men endings. In the paid version, it looks like you can play against Stockfish, and set its rating from 500-2500 elo with a choice of aggressive, active or solid styles. You can set up a position, and play the engine from there. There isn't a tree view or keys. The openings index is sorted by ECO codes with no diagrams or names. Even so, it's the most complete PGN editor/database I've seen for iOS.

In Smallfish, Smallchess and Stockfish, when you try to add a new variation, the app deletes the moves that were there before, so nesting is impossible. They don't seem to allow you to add text comments or NAGs either. Smallfish can display text comments from PGN files you import, but the moves in these comments are not clickable.

Re. Android, Chess PGN Master Pro, Droidfish and Chessbase Online all seem to allow you to annotate games, and add subvariations and some NAGs. The Chessbase app for iOS seems to be more about just accessing their website.

Re. opening repertoires, I haven't tried the iOS version of Arnel Domingo's Chess Opening Trainer, just the Windows demo, but it lets you input your own repertoire, test it, and has trees.

I should also probably mention that there are a number of PGN Editors that you might be able to access online using Safari: Chess.com's Analysis Board Editor, Lichess.org's Board Editor, Apronus and Caissa's Web. A lot of sites also have opening trees, eg. 365chess.com, Chessbase and ChessOK.

# Answer
> 2 votes
I'd want to add details to @A\_passerby's answer. **SmallChess** does support multi-variations. It also supports game annotation. It's a very advanced software. See the screenshots below.

PS: I'm the author of the app.

---
Tags: scid
---


# Question
Title: Choosing the best move in the given position
I was just guessing the best move in the position.(white to move).

I thought Rc1 would be the best move forcing white to exchange the white's dark square bishop and preserving the white's light squared bishop to neutralize the black's light squared bishop . But the engine gives Bxc2 which doesn't makes as sense as the former.I want to know the idea behind engine's move.

```
[FEN "r3kb1r/pp1q1pp1/2p1p3/3nPb2/3P1N1p/PBN1BQ1P/1Pn2PP1/R2R2K1 w - - 1 1"]

```

# Answer
> 5 votes
After 1. Rac1, Black has the intermediate move 1...Nxc3, attacking the rook on d1, which forces White to play 2. bxc3, and then the pawn on a3 is hanging. So Black would likely go 2...Nxe3 followed by 3...Bxa3.

```
[FEN "r3kb1r/pp1q1pp1/2p1p3/3nPb2/3P1N1p/PBN1BQ1P/1Pn2PP1/R2R2K1 w - - 1 1"]

1. Rac1 Nxc3 2. bxc3 Nxe3 3. null Bxa3

```

# Answer
> 1 votes
Rac1 for the following reasons:

1) Bxc2 leaves you with a really good Black bishop vs really bad White bishop.

2) Rac1 has an Xray defense of the Knight on c3, so tactics like Nxa3 (removal of the guard) never come up.

3) Ra2 is soooooo passive.

4) Cute tactics like Nfxd5 never work because black can simply recapture with exd5 (Black shouldn't get jumpy and grab the White Rook due to stuff like Nb5 or something IDK.)

Just a few ideas for you. :)

# Answer
> 1 votes
First look at the position of black's king -- it's still in the middle of the board; most of the time this leaves opportunity for an attack or, at the very least, the initiative. White's attacking area would be on the queen side, so black should not go there with the King and the kingside is weakened due to the pawn being on h4. Also black is underdeveloped due to lack of castling, so the rooks are having a hard time communicating. This gives you the forcing sequence to take advantage of these temporary advantages starting with Bxc2. It should follow something like 1...Bxc2; 2. Rdc1 and wherever the bishop moves you could try something like 3. Ncxd5 and once he takes back with either pawn push 4. b4. Now you are restricting his dark square bishop and preparing to open up a front on the queen side of the board. This should be to white's advantage

```
[FEN "r3kb1r/pp1q1pp1/2p1p3/3nPb2/3P1N1p/PBN1BQ1P/1Pn2PP1/R2R2K1 w - - 1 1"]

1. Bxc2 Bxc2 2. Rdc1 null 3. Ncxd5 null 4. b4

```

---
Tags: strategy, tactics, middlegame, planning
---


# Question
Title: How to set threads number for Stockfish?
How to set number of thread parameter for Stockfish?

I read about Stockfish parameters but there is not description how to set it?

http://support.stockfishchess.org/kb/advanced-topics/engine-parameters

# Answer
Read http://support.stockfishchess.org/kb/advanced-topics/uci-protocol

```
setoption name Threads value 4

```
> 4 votes

---
Tags: stockfish
---


title: Layering multiple chess games

text:
# Question
Title: Layering multiple chess games
Does anyone know if an application exists where you can import multiple PGN files and layer them on top of one another?

It would be interesting to upload say 1,000 games and somehow visualise the most common moves for winning.

I was wondering if something like this exists?

# Answer
If I understood well what you are asking, you are looking for a chess database application. Yes, they exist, and there many examples. Among non-commercial ones you can find Scid and among commercial ones you have for example ChessBase.
> 1 votes

# Answer
Chessbase can display piece probabilities for sets of games.

http://help.chessbase.com/Reader/12/Eng/index.html?000144.htm
> 1 votes

---
Tags: software, pgn
---


# Question
Title: Is there a good example of a paper chess book converted to an ebook?
With Epub, or other ebook formats, one can take advantage of the format and do things that are difficult to do in a paper book. Hyperlinking, extra diagrams, more page breaks - what else? Most books for kindle I can find on amazon have been "converted" from paper books, but have identical content to their paper counterparts. Is there a good example of a popular/good chess book that is much easier to study on electronic device?

# Answer
It depends on what you mean by an "electronic device", but there has been ebook versions of chess books for quite some time, from publishers like Everyman, although admittedly these are nothing like regular ebooks. Of course your device must be capable of running CB reader or an equivalent that can open the chessbase format files.

On the more practical side of things, chess books don't sell very well and formatting even the printed copy is a lot of work. QualityChess has no intention of producing ebooks that can be easily copied:

> Q: Will your books be available as pgn or ChessBase e-books?
>
> A: As long as it is easy to copy these forms of readers, it makes absolutely no sense. Why other companies choose to do this is a mystery.
> 1 votes

# Answer
There are also good examples of electronic chess books like Forward Chess for iOS that has books already converted to interactive format.
> 0 votes

# Answer
I'm unaware of any special epub books. The problem with epub is that you can't move the pieces on the boards.

Most chess book publishers seem to be going with separate apps: Everyman's Chess Viewer reads their pgn books, and the rest use proprietary formats that display a chess board where you can play through the game by clicking on the notation or arrows: e+chess/New In Chess Books and Files (iOS only?), Gambit Publications' Chess Studio, Forward Chess (Quality Chess, New In Chess, Informant, Chess Stars), Chessapps, MChess and Smartchess. Chessapps and Smartchess give you access to an engine for analyzing the positions. Chessapps also lets you save your notes.

I haven't tried it, but there is an app called 'Cbh to pgn' for converting on Android.
> 0 votes

---
Tags: books
---


title: Which is the oldest chess game?

text:
# Question
Title: Which is the oldest chess game?
Chess has more than 1000 years of existence and the pieces got their modern day movements in 15th century Spain. But which is the oldest chess game of which we know the moves?

# Answer
> 10 votes
The oldest recorded game with the modern rules for moves is this game played in 1475. Although it's not clear if castling and en passant were in force.

```
[FEN ""]
[Event "Valencia "]
[Date "1475"]
[White "Francesco di Castellvi"]
[Black "Narciso Vinyoles"]

1.e4 d5 2.exd5 Qxd5 3.Nc3 Qd8 4.Bc4 Nf6 5.Nf3 Bg4 6.h3 Bxf3 7.Qxf3 e6 8.Qxb7 Nbd7 9.Nb5 Rc8 10.Nxa7 Nb6 11.Nxc8 Nxc8 12.d4 Nd6 13.Bb5+ Nxb5 14.Qxb5+ Nd7 15.d5 exd5 16.Be3 Bd6 17.Rd1 Qf6 18.Rxd5 Qg6 19.Bf4 Bxf4 20.Qxd7+ Kf8 21.Qd8#

```

There is also this - http://www.chess2u.com/t8826-oldest-recorded-chess-game \- game which is supposed to have been played some time in the 10th century with old move rules. So, no double first move for pawns, bishops moving like a knight (2 squares diagonally but jumping over the intervening square) and possibly other rules for queens for example.

---
Tags: history, famous-games
---


# Question
Title: I would like an iPad app for annotating my games
I would like an app for annotating my games and/or replay others' games. Do you have any suggestions?

# Answer
> 4 votes
Stockfish works well for this purpose; and it's free software.

# Answer
> 1 votes
Giordano Vicoli's Chess Studio Light allows you to add variations, text comments and some NAGs (!, ?) to the game notation window. Stockfish deletes the main line when you enter an alternate move.

# Answer
> 1 votes
My app, SmallChess allows the most advanced chess analytic.

# Answer
> 0 votes
Chess-wise is the only iOS app that I'm aware of that has an annotation function and an import function.

---
Tags: learning, software, annotation
---


# Question
Title: Are there any very lopsided scores in openings at lower levels?
I was reading this question: How to know how good an opening defense scores, and it got me wondering...Have there been very lopsided opening scores in the lower levels. For example, if we found out that the `Halloween Gambit: 1. e4 e5 2. Nf3 Nc6 3. Nc3 Nf6 4. Nxe5` scores 90% in under 1800 level category it would be quite an anomaly.

Edit:

One kind of an anomaly that I can think of at the top-level is the Traxler:

```
    [FEN ""]
1.e4 e5 2.Nf3 Nc6 3.Bc4 Nf6 4. Ng5 Bc5

```

According to chessgames database black scored 60.1 % wins and 15.9 % draws in 308 games. Of course we don't know relative strength of the players, maybe stronger players had black pieces.

**Edit:**

Tony Ennis pointed out that according to 365chess.com there is no advantage for black in the Traxler.

# Answer
In order to answer your question, I put together a database archive of 30000+ games played in over-the-board tournaments where both players were rated less than 2000. Only one game had the Halloween, and there were few Traxlers. Black died quickly in a handful of Fried Liver Attacks. There were no Parhams 1.e4 e5 2.Qh5 nor Fool's mates.

The Triangle/Noteboom complex scored very well for Black as did the Benko Gambit. 1.d4 d5 2.Nc3?! looked to be a bust, and the Sicilian Grand Prix Attack 1.e4 c5 2.f4?! didn't fare well for White. In the Ruy Lopez, the Steinitz defence 3...d6?! and Cozio 3...Nge7?! led to a lot of Black losses. Rubinstein's line in the French 1.e4 e6 2.d4 d5 3.Nc3 Nf6 4.Bg5 dxe4?! didn't do well either. A lot of patzers fell for 1.d4 Nf6 2.c4 d5?! 3.cxd5! and ended up getting overrun. 1.e4 c6 2.c4! did well against the Caro-Kann.
> 3 votes

# Answer
I don't think that you can statistically prove which openings are better or worse at the lower levels just because of the nature of players themselves. The lower you go, you are going to get the following situations:

1. Haven't studied very many openings
2. Aren't familiar with many positions (open/closed/tactical etc)
3. More likely to fall for or make known move mistakes in later analysis (moves 12+)

As players get more experienced (and thus higher rated), they are much more likely to be able to think their way out of mistakes in openings they are not familiar with, more likely to see forks, skewers, "hidden" threats, that a newer player won't be familiar with. All of these are going to skew any opening validity analysis.
> 2 votes

# Answer
I don't think anomalies can really exist. The reason is that it takes two people, and The Other Guy will not play the variation where he gets smoked. Fool's Mate and Legal's Mate are great examples. A lot of beginners fall for them once, but I suspect that isn't what you're looking for.

Of course, with any opening a player can make a bad move and lose. But I also suspect this isn't what you're looking for.

In my mind, what you're looking for are openings that reward the skilled tactician who studies hard and learns openings well. With the Black pieces, the Sicilian Defense springs to mind - Black opts for an asymmetrical game where "ok" moves by either side can be punished. The King's Indian is similarly aggressive.

On the White side, try sound openings that are not the Ruy Lopez. I've seen some very booked-up beginners. Play an English and see if how they handle it.

Make the opening razor sharp, where the opponent has LOTS of bad choices :-D
> 1 votes

# Answer
one opening which ive used against many beginner's ( i have used this many times on ppl younger than me ) is queens gambit, which can give a very big advantage.

many times Fanchette works as well, because beginners may not properly understand it, and therefore underestimate it.
> 1 votes

---
Tags: opening, statistics
---


# Question
Title: How to know how good an opening/defense scores?
I play Philidor defense, Lolli attack, Fried Liver attack... Other people choose to play well known openings/defenses, so i decided to ask the following questions.

Everyone learns the Najdorf defense because it scores well. (or because Kasparov and Fischer played it). The Philidor isn't as popular as other defenses on the other hand. I have a few questions about that:

* if you wanted to know how well an opening/defense scores, is there an online database that keeps track of all the games ever played and gives you the overall rating of an opening by calculating the average score, or do you take for granted what other players told you?
* How to know if the Najdorf for example is a good opening, maybe Fischer and kasparov won, because they are good players, not because the opening is good. Same question about bad opening and defenses, I mean in the middle game if the player is bad, no opening will let him win, I mean how much can you memorize? How many variations? At some point you have have to rely on your intelligence.
* Don't good openings become bad opening when they become well known? I mean lets use the Najdorf again as an example, because everyone wants to learn it, it is so well known, doesn't that make it a bad opening? The opponent will be well prepared for it.
* And lastly, is it better to play openings/defenses that score well (French defense. Indian etc..) or is it better to play an opening that is not well known and that your opponent didn't learn?

# Answer
> if you decided to know how good an opening/defense scores, is there an online database that keeps track of all the games ever played, or do you take for granted what other players told you?

For instance if you buy Chessbase, it will deliver a big database with some games. There you can look up for the openings, which were played by the big players. I like to hear and take tips from my trainer, rather than believing in some game from two players with \> 2400 Elo. They play completely different, than most of the players. You don't really understand their plans and moves, unless someone comments the game and explains everything. They are not fighting for pieces / pawns, they just fight for one square, which is weak and then in the end-game they will win it eventually, because of this one little weak square.

> How to know if the Najdorf for example is a good opening, maybe Fischer and kasparov won, because they are good players, not because the opening is good. Same question about bad opening and defenses, I mean in the middle game if the player is bad, no opening will let him win.

Fair enough question. If the opening isn't good, wouldn't someone else beat them there (some other good players or an engine)?

The last point is also true. I had many games, where I dominated in the opening but lost it in the middle / end game.

> Don't good openings become bad opening when they become well known? I mean lets use the Najdorf again as an example, because everyone wants to learn it, it is so well known, doesn't that make it a bad opening? The opponent will be well prepared for it.

That's partly true. If your opponent is prepared, you have to be prepared too, but this doesn't mean that it is a bad opening. Especially in Najdorf there are so many variations, you have to know them, when you want to play it.

> And lastly, is it better to play openings/defenses that score good (french defense. indian etc..) or is it better to play an opening that is not well known and that your opponent didn't learn?

This depends on how / what you want to play. I like to play some aggressive stuff. I used to play French defense, but it wasn't my opening. I was losing nearly every game, then I changed to Sicilian and now I win about 25%, draw about 50% and lose about 25%.

If you play something that's unknown, your opponent could still beat you in the opening, because he knows how to play chess (maybe he is also better) and will just spend some time during the opening and analyzing it.
> 6 votes

# Answer
Good openings don't become bad openings when they are known, usually. Usually openings just lose their edge as more effective defenses are found. Every now and then, an opening variation will be "busted" and disappear from professional play.

It is better to know a few variations, and the *reason* the variation works - don't just memorize the moves. Couple that with a good knowledge of middlegame principles and you're going to have some good games.
> 3 votes

# Answer
an opening which worked for fisher etc. might not work for you if you dont understand all the subtle threats that were going on in the background and how to capitalize on them
> 0 votes

# Answer
Question: "is there an online database that keeps track of all the games ever played and gives you the overall rating of an opening by calculating the average score, or do you take for granted what other players told you?"

Straight win draw loss statistics probably don't help you much. Say Anand and Carlsen play ten games with exactly the same opening line. In the first nine games, white wins each time, and then in the tenth game, Carlsen as Black discovers a move that busts the whole opening. The stats for this line would be great +9 -1 for white. However, no GM would play the line knowing of Carlsen's bust. GMs try to get around this by building up their analysis based on best play by both sides rather than the raw stats. It's probably a good idea to take a close look at recent games to see how a given line seems to be faring.

Question: "how much can you memorize? How many variations?"

Practice makes perfect, and I agree with Tony Ennis that understanding the ideas behind an opening might be more important than just memorizing moves. That being said Anand apparently asked Asim Perreira if he could use the latter's app to test his knowledge of his own opening repertoire. Even former world champions need to practice their openings.

Question: "Don't good openings become bad opening when they become well known? I mean lets use the Najdorf again as an example, because everyone wants to learn it, it is so well known, doesn't that make it a bad opening?"

In general, it is a good idea to play openings you are familiar with, but if they don't seem to be working, you might want to try to learn something new. I believe at San Luis world championship, everyone stopped playing the Najdorf for once, and they all played the Ruy Lopez Anti-Marshall. That being said, the Najdorf still has a good reputation at the top level (and the best stats for Black), so I don't think it will go out of fashion.

Question: "is it better to play openings/defenses that score good (french defense. indian etc..) or is it better to play an opening that is not well known and that your opponent didn't learn?"

I think this depends. If you are doing well with your current openings, by all means continue. If you lose, analyze your game, and find that your problems started in the opening, you might want to consider learning a new line. Also if you are playing against an opponent you know, you can guess which kind of opening he won't like.
> 0 votes

---
Tags: opening, strategy, theory, defense
---


# Question
Title: Did Bobby Fischer castle with a pawn promoted to a rook?
I once heard that Bobby Fischer pawn promoted to a rook, and then on a subsequent move, castled with that rook. I have been searching for the move history of this game, if it really did happen, but I haven't been able to find it on the Internet. Am I just searching for a rumor, or did this really happen? Where can I find the move history for this game if it really did happen?

# Answer
> 15 votes
There was a time when the FIDE rules didn't specify that a king and rook need to be on the same rank in order to castle. This meant that, assuming the other requirements for castling were met, it was legal for White to castle with a rook on e8 (or Black with a rook on e1), provided that rook had never moved (which could only happen if it was a promoted pawn). This interpretation was never intended, of course, and the wording has since been fixed.

I've never heard of Fischer (or any other player) taking advantage of this glitch in the rules, but it was used in at least one chess problem.

# Answer
> 14 votes
Not Fischer. But there is the infamous Tim Krabbe vertical castling problem:

http://www.futilitycloset.com/2009/12/11/outside-the-box/

Although it appears this was already illegal as of the problem's publication in 1972.

# Answer
> 3 votes
By FIDE rule 3.8.b, it would not be valid as the rook would have to move.

# Answer
> 2 votes
I ran a search on the games in GM Robert Huebner's World Champion Fischer CD looking for a game where one side promoted a pawn to a rook. Chessbase reports 'no games found.' There were 47 games where someone promoted to a queen, but no games where someone promoted to a bishop or knight. This CD has close to 1000 of Fischer's games.

In the 8th game of Mikhail Tal's match with Bent Larsen at Eersel in 1969, Tal as White checked Black's king, sending it to d8. Later in the game he could have won by advancing his a-pawn, but became worried that Black could develop an attack by castling(!), and so focused his play on preventing this from happening. After the game, a fan asked Tal why he hadn't pushed the a-pawn, and it was only then that Tal realized his mistake. You can't castle once your king or rook have moved.

# Answer
> 1 votes
This won't have happened in a tournament because it is against the rules but could have happened in a friendly blitz game. Given Fischer's character I think it's extremely unlikely even in a blitz game. The promoted rook would have had to make its way back to one of the corner squares and I don't think Fischer would be able to even consider castling with it.

---
Tags: castling, pawn-promotion, fischer
---


title: Playing against imaginary oponents

text:
# Question
Title: Playing against imaginary oponents
Is there a solo computer chess program where you can play against imaginary/fictional/historical characters (and maybe win once in a while)?

# Answer
> 1 votes
Chessmaster is such a program. It is a bit outdated now, but still very usable for the majority of people. The skill cap for the game is well beyond what most club players will ever reach in their lifetime. Some examples of opponents you can play

1. Imaginary - You can play in a Human vs Orc arena, against a commander of the opposing army. There are limited difficulties in this level, so you may have problems playing against the harder opponents. It is also not explicit about which opponents are hard, and which ones are easy, so you will have to test this yourself.
2. Fictional - There are hundreds of fictional people to play against. Each of them have a biography (if you care to immerse yourself) and a picture of a person to help you believe you are playing against an actual person. There are a wide variety of playing styles to help simulate the different kinds of human players you might play against.
3. Historical - There are many famous players who have been simulated into the game, including various versions of Josh Waitzkin at the age of 6 and beyond. Most of the historical players however will be playing at the maximum skill level of the game, since it will be trying to simulate the strength of Grandmasters.

I'd recommend playing against the fictional players, as they are entirely beatable once you learn the rules. You will start out with a rating (around 800 if you are new) and your rating will adjust as you play a few games.

Don't be disheartened if you lose your first few games, this happens to everybody. If you are serious about improving, you will learn something from each loss and eventually your rating will improve, and you can play against stronger opponents.

---
Tags: software, human-versus-machine
---


# Question
Title: What I thought was winning tactic, apparently was mistake
I was recently playing a game as black against the Ponziani when this position came up. (I recommend you flip all the boards to show from black's perspective)

Here's the beginning of the game:

```
[fen ""]
1.e4 e5 2.Nf3 Nc6 3.c3 d5 4.Qa4 Bd7 5.exd5 Nd4 6.Qd1 Nxf3+ 7.Qxf3 Nf6 8.h3 e4 9.Qe3 Bd6 10.d3 O-O 11.dxe4 Nxe4 12.Bd3 f5 13.Bxe4 fxe4 14.O-O Bf5 15.c4 Qf6 16.Nc3 Rae8 17.Bd2 Be5 18.Qg5

```

In the starting position, both sides are apparently equal (0.0)

```
[fen "4rrk1/ppp3pp/5q2/3PbbQ1/2P1p3/2N4P/PP1B1PP1/R4RK1 b - - 6 18"]

1... Qb6 2. Bf4 Bxf4 3. Qxf4 Bxh3

```

After 2.Bf4 black has apparently made a blunder, putting me 90 centipawns ahead. In the game, I spent 5 minutes debating between Qxb2, h6, and Bxf4 finally choosing the last, seeing it as the simplest most effective option.

Apparently, Bxh3 was a blunder on my part, putting white ahead 90 centipawns. (So this move helped white by 1.8) Only, I cannot understand why? I ended up winning the game with the following moves.

```
[fen "4rrk1/ppp3pp/1q6/3P4/2P1pQ2/2N4b/PP3PP1/R4RK1 w - - 0 21"]

1. Qg3 Bd7 2. b3 e3 3. fxe3 Rxf1 4. Rxf1 Rxe3 5. Qf2 Rxc3 6. Qxb6 axb6 7.Rf2 g6 8. Kh2 Bf5 9. Re2 Kf7 10. Rb2 Rc2 0-1

```

I feel like the decision to play Bxh3 was justified and what helped me win the game. Yet the engine disagrees. Could somebody tell me what the problem with Bxh3 was?

# Answer
First of all, I don't think it is productive to call moves "blunders" when they're just not the best moves according to the computer. Chess is a game between humans. I like to reserve "blunder" for moves that are really terrible.

That said, after 20...Bxh3, Komodo 9.02 recommends 21.Qe3 for White, forcing Black to exchange queens, after which material is equal (remember that you were down a pawn to start with) and it likes White's position better.

It prefers to delay the discovered attack on the queen by playing 20...e3, threatening 21...Bd3 (winning an exchange), which is really hard for White to deal with. Komodo's line is 20...e3 21.fxe3 Bd3 22.Qxd4 Bxf1 23.Qxb6 axb6 24.Rxf1 Rxe3 and Black is up an exchange for a pawn.
> 7 votes

---
Tags: analysis, engines, strategy, tactics, blunder
---


# Question
Title: Reading UCI Engine output in Arena Chess
So for the most part I understand what I am looking at, but i have two questions about the first piece of data. Here is an example that I am looking at.

Firstly, the first column has values 1/4, 1/8, 2/17, 3/17. I'm pretty sure the numerator of those fractions indicates the depth of the search, but I am confused about the second number, my only guess being that it is the search depth of all non-quiet positions? IDK

Secondly, When I see a depth of 3, i expect to see a move order of length 3, but in the 3/17 search I am given a 6 move long line of play. Is this due to non-quiet nodes? The captures in the line make me believe so.

Thanks, any help, insight, and resources are appreciated.

# Answer
> 4 votes
http://www.chessforums.org/general-chess-discussion/9079-chess-engine-output.html

> It’s the “search depth.” It tells you how deep the search has gone. The value is in “ply” or half-moves. The first number gives you the “brute force” depth, the second is the depth to which certain critical lines have been investigated. For instance a display of “depth = 12/30” means that the program has looked at every continuation to a depth of 12 ply (six moves), while some promising or dangerous continuations are being examined up to a depth of 30 ply (15 moves).

Please note chess engine always report in "ply", half-move.

---
Tags: engines, programming, uci, arena
---


# Question
Title: When to give up on winning a game e.g. due to material
In what situations is it impossible to win for a player? For example due to not enough material or the composition of the material is not useful. I guess for example when you only have a king and a knight left or so and the opponent has far more pieces? I'm looking for the (few) hard cases where "you can't win". For example when you only have a king.

# Answer
There are very few positions in which it is actually impossible to win although you are up material. Basically only KN vs K or KB vs K.

Then there are positions which can be won, but this would require such egregious errors by your opponent, that in practice a draw will inevitably be agreed. Examples are KNN vs K, KBB vs KB, KR vs KB.

And then there are theoretically drawn positions which give you very real winning chances even against strong players. KR vs KN, KRB vs KR, KQ vs KNN.

There are also known "fortresses" where the stronger side cannot break through once the weaker side has achieved a certain setup. Here is one famous (and relevant) example:

```
   [White "The wrong"]
   [Black "bishop"]
   [FEN "k7/8/8/PK2B3/8/8/8/8 w kq - 0 13"]

```
> 4 votes

---
Tags: draw
---


# Question
Title: Is there any opening line which is downright catastrophic?
I have played 1.a4, h4, f4 in an engine and it gave me the opening line's name. I mean, how could it be considered a line as it, at least IMO, don't do anything that defines a good opening. (fight for center, develop your pieces etc.)

# Answer
> 4 votes
If you mean "Is there any first move for white which is catastrophic?" then the answer is "No". There are first moves for white which look bad. Na3, Nh3 and f3 would be my candidates but they are not catastrophic.

Na3 could be followed up by moves like b3, c4, Nc2, Bb2, for example, to get a playable position. Perhaps not the best use of first move advantage but certainly not catastrophic.

The problem for black when white makes a "bad" first move is to try and steer the opening into one where the "bad" move is really a bad move in the context of that opening or at least irrelevant so that white's first move advantage has gone.

White's contrasting problem is to try and steer the opening towards one where the "bad" move becomes good. For instance, after 1.h4 if white can steer black into fianchettoing his king's bishop and castling kingside then 1.h4 could become a strong threatening move.

If by "opening line" you mean a sequence of moves then, yes, there are catastrophic lines and yes, they do often have names. The most famous is probably Scholar's Mate:

```
[FEN ""]
[Event "Scholar's Mate"]

1. e4 e5 2. Qh5 Nc6 3. Bc4 Nf6?? 4. Qxf7#

```

The shortest possible mate and so the most catastrophic is Fool's Mate:

```
[FEN ""]
[Event "Fool's Mate"]

1. f3 e5 2. g4?? Qh4#

```

# Answer
> 2 votes
I would say the value of an opening is conditional on your opponent:

* **You against a computer with almost perfect play**: all openings are bad. You'll lose anyway (unless you are a super GM), but some openings are worse than others.
* **You with the help of a computer against another computer or player with a computer**: some openings lines are bad, some are ok, and some are good. A computer will not forgive your choosing an opening line that leaves you in an inferior position. With most openings you'll end up in draw. And if you want to win you have to choose some anti-computer opening.
* **You against a human player**: to estimate the value of an opening line against a human player you have to evaluate which is their opening repertoire and their playing level relative to yours and which is the type of competition. Against a player with a similar rating, you might try to surprise them with an uncommon opening (that you have studied well) to get them out of book. This strategy can be more useful in rapid and blitz games, since it is more probable the opponent will make an error you can use in your advantage. For example, Carlsen played 1.a4 against Radjabov in the World Blitz Final in 2012 (and won). But with a player with much more experience than you, it might not work anyway.

# Answer
> 1 votes
My favorite catastrophe is probably the Blackburne Shilling Gambit, probably because I fell for it once :-S.

```
[Title "Blackburne Shilling Gambit"]
[fen ""]

1.e4 e5
2.Nf3 Nc6
3.Bc4 Nd4?!
4.Nxe5 Qg5
5.Nxf7? Qxg2 6.Rf1 Qxe4+ 7.Be2 Nf3#

```

Gotta be good for White, right? Grabbing the f7 pawn AND forking the black queen and rook! While White's rook is easily saved from the Qxg2 threat via Rf1. Heh.

---
Tags: opening
---


# Question
Title: How do you draw in an opposite color bishops endgame with two pawns down?
Is it possible to draw in such an endgame? Are there exceptions? If so, what are they?

# Answer
> 9 votes
> How do you draw in an opposite color bishops endgame with two pawns down?

Fortress is your only chance in such a position.

* You **must** base your defense on the color of your bishop.
* Make your bishop a "bad bishop", so he can defend your pawns, if you have any.
* You will stop opposing passed pawns by controlling the diagonal that is the same color as your bishop.
* Exchange as many pawns as you can.
* Force stronger side to put his pawns on the color of **their** bishop.
* Put your pawns on the color of **your** bishop.
* Your king must fight the enemy one, by "cutting him off" from helping his passed pawns promote. You achieve this by posting your king on the square that has the same color as your bishop, when blockading opposing passers.

Below diagram shows what a fortress is:

```
[Title "Weaker side builds a fortress"]
[fen "8/2k5/4Bp2/2b1p1p1/4K2p/7P/8/8 w - - 0 1"]

```

White will move the bishop along the `c8-h3` diagonal, and there is nothing Black can do to set his pawn majority into motion.

There is no way for him to break the fortress, since White's defense is organized on the light squares, which is the color of his bishop.

Another example that illustrates the points listed above:

```
[Title "Another fortress"]
[fen "5k2/p2K1P2/P3P3/2b5/2B5/8/8/8 w - - 0 1"]

```

Again, we can see that defense is based on the squares of the same color as the bishop is. In this case, Black defends on the dark squares.

As stated above, Black has "bad bishop" but this is good thing here, since White can not win the `a7` pawn.

Also, this example demonstrates how weaker side uses bishop and king to "cut off" enemy king from crucial promotion squares. White can not break the blockade, nor can he create zugzwang so the position is a draw.

Since you have asked specifically about endgame with 2 pawns down, there are some tips that can further help you. Read on...

*Battling 2 connected passers:*

* Weaker side positions the bishop so it attacks one, and controls the other pawn;
* Passers on sixth rank usually win, otherwise high probability of a draw.

Again, simple illustration:

```
[Title "Illustration of a drawing concept"]
[fen "8/2b1k3/8/1B1PP3/3K4/8/8/8 w - - 0 1"]

```

Black attacks `e5` pawn, and controls `d6` square. That way, if `d6` is played, Black sacrifices bishop for 2 pawns and draws.

Remember this rule, as it is the only way to draw in such positions.

*Battling 2 widely separated passers:*

This one is very hard, as stronger side has great winning chances. You must apply the "one diagonal" defense -\> control both passers on the same diagonal. That is your best bet. Use king and bishop to push away enemy king from key promotional squares. Below is an example of what I was talking about:

```
[Title "The one diagonal"]
[fen "8/2bB4/2P5/6k1/4K3/5P2/8/8 w - - 0 1"]

1. Kd5 Kf6! {The white king will not get to e6} 2. Kc5 Ke7 3. Kb5 Bf4 4. Kb6 Kd8 1/2-1/2

```

This example also demonstrates how to deploy the principle of pushing away ( or blocking ) the enemy king, by using bishop and king synergy.

Remember, you must keep your pieces mobile, and it is absolutely mandatory that you can reach both passers with your king as fast as the opposing one.

You should be able to establish diagonal control easily, however, reaching with king on time is not so simple. If you manage to be there on time to establish blockade or push away the enemy king, then you will draw.

> Are there exceptions?

Yes! Chess would be poor and dull game if there were no exceptions to its "rules"!

> If so, what are they?

OK, so far we looked at the principles for the defender, now it is time to see what options stronger side has.

First off, stronger side fights to prevent the creation of the fortress. This is done by taking over control of the squares your bishop controls. Thus the stronger side wants to have "good bishop", so it can "push away" weaker side's bishop. This plan is very risky, but it is the only way to win ( generally speaking, of course; it all depends on the actual position).

Sometimes you will have to sacrifice a pawn or two in order to break the fortress, this is not unusual!

Your best bet to win is to create separated passers, that are separated at least by 2 files or more -\> the more the better!

Below is the famous example of how stronger side breaks the blockade and wins with the separated passers:

```
[Title "Kotov vs. Botvinnik, 1955"]
[StartFlipped "0"]
[fen "8/8/4b1p1/2Bp3p/5P1P/1pK1Pk2/8/8 b - - 0 1"]

1... g5!! 2. fxg5 (2. hxg5 h4 3. Bd6 Bf5 4. g6 Bxg6 5. f5 Bxf5 6. Kxb3 Kg2 -+)  2...d4+! 3. exd4 (3. Bxd4, Kg3 4. g6 Kxh4 5. Kd2 Kh3!! 6. Bf6 h4 7. Ke2 Kg2!) 3...Kg3! (3...Kg4? 4. d5! Bxd5 5. Bf2 {White draws}) 4. Ba3 (4. g6 Kxh4 5. g7 Kg4 -+) (4. Be7 Kxh4 5.g6+ Kg4 -+) 4...Kxh4 5. Kd3 Kxg5 6. Ke4 h4 7. Kf3 ( 7.d5 Bxd5+ -+ ) 7...Bd5+ 0-1

```

Black wins because he will win the bishop for a pawn. His own bishop can defend the remaining pawn and keep the opposing one in check. Therefore, White can not exchange pawns and save a draw.

From the above game, we can derive the following rule:

* Stronger side moves king towards the pawn opposing bishop is holding back
* Stronger side tries to create separated passers, and the more distant form each other they are the better!

As for connected passers, your only chance is to get them to the sixth rank. Then there is a chance to win by creating zugzwang. Below diagram is great illustration of this principle:

```
[Title "Stronger side wins with connected pawns"]
[fen "3k1b2/8/3PP3/1B1K4/8/8/8/8 w - - 0 1"]

```

If you remember from before, weaker side must attack one pawn, and control the other.

Here, **at the moment** Black does exactly that. His defense holds since White can not advance any further.

Still, White can play a waiting move `1.Kc6`, and force Black to abandon the control.

This type of positions is the only way for you to win with connected passers, otherwise weaker side holds as explained before.

## OUTRO:

I have tried to minimize the amount of posted content, so you don't get overwhelmed.

In case you need further info start here.

If you have follow up questions, leave a comment.

Best regards and god luck!

# Answer
> 9 votes
Yes, if the pawns can be blockaded it's often an easy draw. One example:

```
[fen "8/4k3/4P3/3P4/2B1K3/b7/8/8 w KQkq - 0 1"]

```

As long as the black bishop controls d6, the pawns aren't going anywhere.

But two pawns are two pawns. If they are farther apart and far progressed often one pawn wins the bishop and the other pawn wins the game, or one pawn sacrifices itself so the other one cannot be blocked by the bishop anymore. But this depends heavily on the specifics of the position.

# Answer
> 9 votes
There are a lot of cases where two pawns is not enough to win an opposite bishops ending, but generally it depends on the position. If the defending side manages to block the pawns on the color of the attacking bishop (like @BlindKungFuMaster's position), it is usually a draw. Especially when they are on the same diagonal, as then *zugzwang* is less likely. The defending player usually needs **both** the king and the bishop for the blockade.

An very fine example of a winning position is this one:

```

      [FEN ""]
      [Event "Linares"]
      [Site "Linares ESP"]
      [Date "1998.03.04"]
      [EventDate "1998.02.22"]
      [Round "10"]
      [Result "0-1"]
      [White "Veselin Topalov"]
      [Black "Alexey Shirov"]
      [ECO "D85"]
      [WhiteElo "?"]
      [BlackElo "?"]
      [PlyCount "106"]
      [StartPly "93"]

      1.d4 Nf6 2.c4 g6 3.Nc3 d5 4.cxd5 Nxd5 5.e4 Nxc3 6.bxc3 Bg7
7.Bb5+ c6 8.Ba4 O-O 9.Ne2 Nd7 10.O-O e5 11.f3 Qe7 12.Be3 Rd8
13.Qc2 Nb6 14.Bb3 Be6 15.Rad1 Nc4 16.Bc1 b5 17.f4 exd4 18.Nxd4
Bg4 19.Rde1 Qc5 20.Kh1 a5 21.h3 Bd7 22.a4 bxa4 23.Ba2 Be8
24.e5 Nb6 25.f5 Nd5 26.Bd2 Nb4 27.Qxa4 Nxa2 28.Qxa2 Bxe5
29.fxg6 hxg6 30.Bg5 Rd5 31.Re3 Qd6 32.Qe2 Bd7 33.c4 Bxd4
34.cxd5 Bxe3 35.Qxe3 Re8 36.Qc3 Qxd5 37.Bh6 Re5 38.Rf3 Qc5
39.Qa1 Bf5 40.Re3 f6 41.Rxe5 Qxe5 42.Qa2+ Qd5 43.Qxd5+ cxd5
44.Bd2 a4 45.Bc3 Kf7 46.h4 Ke6 47.Kg1 Bh3 48.gxh3 Kf5 49.Kf2
Ke4 50.Bxf6 d4 51.Be7 Kd3 52.Bc5 Kc4 53.Be7 Kb3 0-1

```

Black played the fantastic move 47 ... Bh3!!, sacrificing the bishop to gain a critical tempo with the king. White's king could not join the bishop in time for the blockade.

---
Tags: endgame, bishop-endgame
---


title: Indian theme in real life

text:
# Question
Title: Indian theme in real life
We all know this beautiful theme of self-interference.

```
[Title "Loveday, mate in 3"]
[fen "3R4/5K2/8/4k1P1/4p3/7B/4p3/8 b - - 1 0"]

```

Solutiom:

> 1. Bf1 d6 2. Re2 Kc4 3. Re4#

Has such a motive ever occur in an OTB game?

# Answer
> 6 votes
The Indian theme appeared in a game between Rudolf Spielmann and Siegbert Tarrasch (San Sebastián, 1912):

```
[FEN "..."]
[Event "San Sebastian"]
[Site "San Sebastian ESP"]
[Date "1912.03.12"]
[EventDate "1912.02.19"]
[Round "17"]
[Result "0-1"]
[White "Rudolf Spielmann"]
[Black "Siegbert Tarrasch"]
[ECO "C80"]
[WhiteElo "?"]
[BlackElo "?"]
[PlyCount "82"]

1. e4 e5 2. Nf3 Nc6 3. Bb5 a6 4. Ba4 Nf6 5. O-O Nxe4 6. d4 b5
7. Bb3 d5 8. a4 Nxd4 9. Nxd4 exd4 10. Nc3 Nxc3 11. bxc3 c5
12. axb5 Be7 13. Qf3 Be6 14. Rxa6 O-O 15. cxd4 c4 16. Ba2 Rxa6
17. bxa6 Qa5 18. Bb1 c3 19. Qg3 Rc8 20. f4 Bf5 21. Re1 Bf6
22. Kh1 h6 23. h3 Rb8 24. Be3 Qxa6 25. Rd1 Qa1 26. Qe1 Be4
27. Kh2 Be7 28. Qf1 f5 29. Re1 Bh4 30. g3 Be7 31. Bf2 Bd6
32. Rc1 Kh7 33. Re1 Rb6 34. Rc1 Ba3 35. Re1 Qb2 36. Qe2 Rb4
37. Rg1 Rb6 38. Re1 Qb5 39. Qh5 Qxb1 40. Rxb1 Rxb1 41. g4 Bc1
0-1

```

I copy Tarrasch's comments to move `41...Bc1` from here and the original source is Tarrasch's book The Game of Chess (London, 1935), p. 422-423.

> "The move Bc1 is analogous to the blocking move of the 'Indian Problem'; intrinsically it is an extraordinarily unlikely, even ugly move, since the Rook which is to give mate is masked. The 'Indian' character of the move is seen in the following variation: `42. Kg1 Be3+! 43. Kh2 Bxf4+ 44. Bg3 Th1#`. Another possibility is `42. Be1 Bxf4+ 43. Kg1 Bg3!` followed by mate or the gain of the Queen. The main variation is `42. Kg3 g6 43. Qh4 Bxf4+! 44. Kxf4 g5+`, and Black wins."

---
Tags: tactics, problems, master-games, otb-chess
---