# Question
Title: What is the average length of a game of chess with only random moves?
The famous Shannon number, 10^120, an estimated lower bound on the number of possible chess games, is based on the assumption that a typical game lasts 40 moves.

In games between skilled human players, this average game length seems to be about right (see this question), but if we want to count *all* possible chess games, then we also have to include the vast majority of games where the moves don't have any purpose or sense whatsoever. Such a game with random moves would surely be likely to last more than 40 moves?

So what is the average game length of a random game? This should be easy enough to simulate on a computer.

# Answer
> 5 votes
I reran the script from the answer GloriaVictis linked.

For a twenty-five thousand games the average length was 357 ply.

# Answer
> 5 votes
An interesting question with which I've done significant exploration. My program *Symbolic* can generate random games using the /dev/urandom pseudorandom generator to any length. For a recent run of ten million random game, the average length was 342.064 ply.

```
[] rg 10000000
   Checkmate  1527544 0.152754
  FiftyMoves  2241451 0.224145
Insufficient  5358614 0.535861
  Repetition   258221 0.0258221
   Stalemate   614170 0.061417
Average ply length: 342.064
Maximum ply length: 974

```

# Answer
> 0 votes
One estimate of the length of a game of chess with all random moves might be 90 moves. This is the length of an average game as used by Shannon (40 moves), with 50 more moves added until the 50-move rule takes effect (at which point the game can be drawn if one player requests it). The first 40 moves will certainly simplify the board, as pawns can only move forward, and must start to capture other pawns and pieces. There may also be some promotions of pawns into queens or other pieces, and the pieces in general will be "thinned-out" from random captures. After this, pieces will continue to move, and still with no purpose. After 50 moves of no captures and no pawn promotions, either side can claim a draw. If we assume that a random player might also request a draw at a random moment (once being allowed to do so), then such a request is inevitable, and the game will end.

---
Tags: statistics, game-complexity, game-length
---


# Question
Title: Can the total number of possible wins/draws/losses be calculated?
http://s13.postimg.org/miyhhh113/chess\_finite\_graph.png

I'm trying to imagine the finite graph of all positions in chess. Due to the sheer number of possible positions, it is impossible with current technology to build an exhaustive database. Such a database would require more than 100 zetabytes of storage.

But even if we can't store the positions exhaustively, would it be possible to count winning lines for each side? That is, can the number of arrows going to *Draw*, to *Black Won*, and to *White Won* be determined mathematically? And if so, would White have more winning arrows than Black?

# Answer
Theoretically, we don't know, because we can't calculate it yet. Chess is not solved as an universal and general problem and we don't know that if two *gods* play chess in an infinite manner, which color wins or maybe it's just a draw.

Statistically, you can gather data from chess databases in websites, tournaments and computer tools to have an estimation. For example see this online databases.
> 6 votes

# Answer
The answer to this question is most probably highly influenced by the style of play (i.e. perfect play, grandmaster-level, intermediate level, junk-play, or pure-random moves).

In high-quality play between chess engines (grandmaster level) I believe the ratio is about 35% (White wins), 41% (Draw), and 24% (Black wins). This is based on referenced information from Wikipedia.
> 0 votes

---
Tags: statistics
---


# Question
Title: Is the Smith-Morra gambit still worth playing at a ~1600 level?
I've been playing the Smith-Morra Gambit (e4 c5 d4 cxd4 c3) against the Sicilian defense for about 2 years. I have a tournament coming up in 3 days and I am beginning to doubt if the Smith-Morra would suffice. I like attacks and do not enjoy slow maneuvering play (which is why I do not play queen's pawn). Is there any reason I should change my response to the Sicilian? It seems like 3 days is not enough time to learn the thousands of variations in the Sicilian. And even I understand good play by black means that I am down a pawn for good.

FYI, I have an FIDE rating of 1398 and it seems to me that my opponents will be rated average of 1600.

# Answer
> 6 votes
The gambit is perfect for amateurs, the gambit is tricky and could be deadly if Black underestimate White's attacking potential.

I've personally used it to beat players around FIDE 2000, so it's fine for you to try.

# Answer
> 6 votes
I've been playing the Smith Morra Gambit for about 5 years and am rated around 2000 FIDE currently. I regularly play the Morra(it is my only response against the Sicilian), and my performance with it is usually 100 or more points above my rating. Thus, the Morra definitely can be played against stronger opposition. However, if you are serious about continuing the Morra throughout your chess career, you must buy Mayhem in the Morra by Marc Esserman. Any serious morra player has this book.

# Answer
> 2 votes
I'm rated around 1850 FIDE (approx as converted from the UK system). I play the Morra and it does me just fine - I've drawn against 2000+ players with it and do well against similar rated opponents. So if you enjoy it, play it - professionals excepted that's why we play chess!

# Answer
> 2 votes
Yes. The Smith-Morra will suffice if you're playing 1600s. If you lose, then your problem is likely not because of the opening.

The Smith-Morra gambit is for bottom feeders. You can still be 2000 FIDE and play it. But that's probably the rating threshold where you should switch to a more mainline opening.

I've actually seen an 1800 rated player beat a grandmaster online on ICC with the Smith-Morra Gambit!

Therefore, it depends on what you use chess for; the smith-morra gambit is absolutely working at a 1600 level, it's not like a grandmaster can lose to 2000s by playing the Smith-Morra gambit, although he'd (or she'd) probably have to switch for when playing 2200s.

If you want to be titled, you have to play the main lines (because then you'll never have to switch again, but also there's no risk because it has basically been proven to be sound). I absolutely love Quality Chess's motto: "Tired of getting bad positions? Try the main lines!"

P.s. A good line for black against the smith morra gambit would be the Siberian trap line. Even if white doesn't fall for the Nd4 trap, black can still get a safe position (and the computer evaluates it as 0s).

Edit: I just realized that this was too late to post, because you wanted to know if you could use it in your upcoming tournament.

# Answer
> 1 votes
My experience has been that even stronger players don't like playing against the Smith-Morra because it takes them out of their "book". When the clock is ticking and they have to solve opening problems over the board that they might not be all that familiar with, that's a great equalizer. It takes them out of their comfort zone. If someone's playing the Sicilian, it's a good bet that they know the standard lines. I like using the Grob against mid-range players for the same reason. In a tournament where I had beaten and drawn Experts in the first 2 rounds, I played a Sicilian against a category 1 player in the 3rd round who used a Smith-Morra and won after I got lost in the complications, ruining what had been a good tournament for me. If you're playing against category 1 or better players, that might be a different story, but at the level you indicate, I see no problem with using it, particularly since you have a good working knowledge of it as you indicate.

# Answer
> -1 votes
http://www.chessgames.com/perl/chessgame?gid=1814884

I think it's safe to say that the Smith-Morra is playable at the 1600 level.

---
Tags: tournament, sicilian-defense, attack, smith-morra-gambit
---


title: Why chess styles?

text:
# Question
Title: Why chess styles?
Before posting this question I went through a lot of Q&As on this list.

https://chess.stackexchange.com/search?q=style

But I still have this question without solid answers.

**Question**: I know what a chess style is, and that different players can have their own styles. My question is on the "why" factor. Why do we have such styles defined? Are they defined just for the sake of analysis, or are they used for something? Are they useful for players? If yes how?

How can knowing your style or others' styles be important/useful to you? Can we use that to improve ourselves?

This is not a direct question. I just need some answers as per your opinion. Appreciate your ideas.

# Answer
> 5 votes
Chess is not a game that solely exists in 64 squares. Much of chess exists in our minds, and the constructs we use to process those 64 squares into beautiful and powerful games. Naturally, some approaches work better than others. Kasparov's approach to chess in his mind is, needless to say, quite a bit better than my mental approach to chess.

So, as with any game, we try to learn how to grow. We study things like end game puzzles and openings to refine our conscious approach to the game. However, a tremendous amount of human processing goes on subconsciously. We need ways to refine those subconscious methods as well. This gets into the feel of the game, or the spirit of the game. For this, we study "styles."

The funny thing about the subconscious is that it's always working. If you teach your subconscious to think a particular way about a particular chess position, it doesn't file those neural circuits away as "for Chess purposes only." It finds ways to use them in your daily life. The dual of this is true as well. Your subconscious will draw on how you handle your daily life to play chess. If there was only one way to live life, there might be only one style of chess worth playing. However, there's more ways to live life than I can count, and each brings a different set of tools to the chessboard. The best learn how to bring their Chess life and their external life into harmony, so that they can use both in all circumstances.

So we study styles to see things that have worked for other people in their lives. Then, we adapts those styles to work within our own lives.

# Answer
> 7 votes
Well, I think that knowing what type of style suits you best would be helpful in winning. If you are good at tactics, playing an open game like the Giuoco Piano where the pieces come in contact sooner would be more desirable than playing a closed one like the Queen's Gambit where a lot of maneuvering would go on before the game opened up and became more tactical. Similarly, knowing your opponent's style would be helpful in deciding what type of opening to use against him. If he's a strong tactical player and begins with 1.e4, if tactics isn't your forte, you may want to consider something like the French or Caro-Kann rather than playing 1..., e5 and facing the Giuoco Piano, Ruy Lopez or some gambit like the King's or Scotch. Against 1.d4, a positional player would stick to the normal closed Queen's Gambit Declined defenses rather than something like the Budapest Gambit that opened up the game. I might add that playing open games is normally recommended for a novice to improve his tactical skills before moving on to closed games.

# Answer
> 2 votes
The answer to why different players have different styles is already in the question: because they are different. As in all aspects of our lives, in a game of chess we have options, and in the same way that different people approach their life in different ways, so do the chess players.

For most of the casual and even some tournament players, knowing the style of their opponent is useless: they play the game in the same way against all of their opponents. In higher levels however, knowing the style of the opponent may benefit you since you can change the nature of the position in your opponent's detriment: one usually does not want to play sharp and tactical games against a younger player or a player famous for their attacking abilities, and similarly one would not want to enter dull and even positions against a strong positional player. In this regard, I would not say that they are defined for the sake of analysis, but on the converse, analyzing a player's games will give you an idea of their style (and hence grant you an advantage).

Hence, style can mostly be characterized by personal preference. Knowing one's style can help you when choosing new openings and lines, ideally you would want them to suit your style. It can also help during a game, in case one detects that the best moves lead towards a position that does not suit one's style, it would be desirable to muddy the waters (if one tends more towards tactical games) or to exchange pieces or fix the pawn structure (if one tends more towards positional games).

Using these advantages to improve one's game would be to know our limitations and weaknesses, and work on them (like most of the top players do). However, this is a somewhat subjective answer, since other players would simply choose to enter tactical variations when faced against a quiet opening, or in the converse to play solid against wild openings. Even if I prefer the first option, the second is a completely viable strategy (as evidenced by some of the best players having an extremely limited repertoire that they know in great depth).

Disclaimer: for illustrative purposes, only two styles have been mentioned above, and a short comparison has been made. There are obviously many different styles, and this is in no way an exhaustive list.

# Answer
> 2 votes
Because of two reasons I can think of:

1. Chess isn't always about a single perfect move (especially in the opening!), there tends to be 1 or 2 or 3, even 10 other moves that are exactly the same level of strength. Specifically speaking of the opening, styles of the positions you reach can differentiate based off what you play.
2. We do it because people naturally prefer or do favorable in one specific type of position over another. Some players are natural born attackers and very talented at it, so they will play openings that are more geared towards attacking; they will play into their strengths and have a better intuition of what to play. Other players are more positional and have a talent for identifying maneuvers and plans, so they will prefer 'slower' lines like the Closed Ruy Lopez.

Also, to the last question, yes, we can try to identify our styles and our talents in chess to improve our openings and get a better feel for what positions we should reach.

# Answer
> 1 votes
The sole purpose of coining the term "chess style" is to categorize the way top players think. It is also used for adapting and making it so lower-level players can copy the way they feel like doing it.

Style is important even in chess because it is your natural thinking process and acts like a mirror. It helps you to improve more by making the style as a reflection to your own personality when you see the mirror. It acts like a rhythm to a music where you can determine the future moves when you act upon it.

# Answer
> 1 votes
Personality, in any aspect of life, is a complicated thing. To speak of style is a way to reduce personality to a small number of options (romantic, classical, scientific, etc..) in order to simplify description/discussion, but it will often be an oversimplification, and therefore unreliable.

Perhaps I make a move that allows an unclear attack in response that I am really rather afraid of, but I tell myself that it would not be in my opponents style. If s/he is a good player, they will do their best to arrive at an objective judgement regardless of style, but style will probably influence what they actually play.

# Answer
> 1 votes
"Style" is just a very terse way to express a complex idea. By having a common language regarding chess "styles" you can quickly quantify and communicate an idea with other players.

It aids in analysis and communication between people who enjoy the game.

It is similar to "theory" in music. You don't have to know the language of musical theory, but if you do, you can communicate with other musicians and critics very quickly regarding what is otherwise a difficult thing to express.

---
Tags: style
---


# Question
Title: How to bring tactics skills into the actual play?
According to few popular sites, my *tactics* rating is consistently about 400 points above my *game* rating (say, 2200 vs 1800).

Of course, partially it could be a fault of the process: when a tactics engine gives you a position, you *know* that there is some tactics. On the other hand, I almost always find combinations while observing other people play, in real time - and miss quite many while playing myself. It seems that I become too preoccupied with the plan, or something like that.

Any ideas how it can be healed?

# Answer
> 5 votes
As you have noted yourself, an important difference between solving tactics and finding tactics during a game is that you know that there is something interesting when solving tactics. There are a couple other important differences. In a game, it comes down to your ability to discern a critical position from an ordinary one that only requires positional consideration. In long time controls, it is advisable that you **treat every position as a tactical puzzle**, at least for some amount of time. Of course some positions you know are not critical, but spending a little bit of time checking every move will help you be more tactically aware. And of course, you got to watch out for your opponent's tricks too.
I will ignore the question relating to having a 2200 tactics compared to 1800 elo because the scale may be different between the two and an 1800 rated player could have a range of tactical ability anyways.

# Answer
> 2 votes
You have to have a strategically better position in order to 'force' tactics. Focus on strategy.

Tactics are how you win games, but Strategy is how you prove that your pieces and pawns are more impressive than your opponent's. Don't just think in terms of 'okay I'm going to play Nd4 to threaten a fork', but instead 'I'm going to play Nd4 to reroute to b3 so that I can push c5 and my knight will be on c5 putting a lot of pressure on critical points b7 and d7. Even if these threats are met, I will have a slight advantage after I bring all my pieces to the center.'

# Answer
> 1 votes
My explanation is that the tactical rating has nothing to do with your chess rating.

Chess rating is measured by playing a chess game, not by solving chess puzzles. Those sites offering rating almost always overestimate your ability because:

* They don't know how to do it statistically (you really need a PhD statistician to do it properly)
* They want to make you happy

# Answer
> 1 votes
You're right that knowing a problem exists is the first step on the road to the solution, as opposed to a game situation when you aren't always aware that you're at a critical juncture. You have to treat every game situation initially as if there's a tactic present and convince yourself that there isn't before moving on. I've experienced the same problem that you have of missing tactics in my own game whereas I see them when I observe someone else's game. As you imply, I think that has something to do with the fact that you're in the middle of some plan in your own game and don't stop to see if there's something else you might have missed. As Emanuel Lasker once said, "When you see a good move, look for a better one". Maybe pausing during your game occasionally to look away so that you see the position with fresh eyes when you look back at it might help. That would be akin to your looking at another game position where you haven't followed the sequence leading up to it and see a tactic, as you say happens. Or maybe consider it parallel to how a computer generates a move, assessing each new position as it occurs.

# Answer
> 0 votes
There can be a few reasons behind this.

* Maybe you are solving the tactics based on a theme which does not reflect in your style of play.
* Nowadays, tactics can be categorized based upon the openings, and the middlegames. You may be practising middlegame positions based upon QGD, and playing Sicilian where the board dynamics do not match.
* Please do not look at the board constantly during a tournament game, and it is advisable to sometimes look here and there, looking at other people's games which would distract you for some moments and then give you a fresh look into your position.
* Tactics arise when pieces are in touch with each other, or have contact. When pieces are in contact, make yourself a little more aware and careful, which would help you in finding the better moves.

# Answer
> -1 votes
Maybe because you become unaware of tactical indicators in your own games. Unprotected pieces, double attack, overprotection, intermediate moves/checks, etc.

---
Tags: learning, tactics, training
---


title: Do you accept takebacks?

text:
# Question
Title: Do you accept takebacks?
If somebody playing with you propose a takeback, how often will you accept it? Do you know if takebacks are allowed on tournaments?

# Answer
> 4 votes
Regarding tournaments, according to the FIDE rules, takebacks are not permitted. Section 4.6:

> When, as a legal move or part of a legal move, a piece has been released on a square, it cannot be moved to another square on this move. The move is then considered to have been made:

(The rest of section four has more rules about touching a piece, moving a piece, capturing a piece, and the like - but the gist of the answer is there: once a move is made, it has been made.)

Regarding casual games... that's entirely up to you. In general, I prefer touch move and no takebacks regardless of the game - but sometimes, if it was a very good game, it's nice to say, "sure, you win... but what would have happened if..." and play it out a different way.

# Answer
> 3 votes
I'll generally accept takebacks when playing online if I suspect the move isn't what my opponent actually intended, and have actually been known to request them under the same circumstances (I can't tell you how many times I've tried to castle on the Lichess mobile app, and ended up just making a king move instead by accident, just because of how the user interface works).

I never propose takebacks in over-the-board play, and generally wouldn't agree to an opponent's takeback proposal unless it's a very casual "just playing to while away some time" type of game - when playing over-the-board, it's unlikely to make a move that isn't what you actually intended. While I haven't really thought about it to any extent, I think my boundary line for this would probably be, if the game is serious enough that a clock is involved, then it's serious enough for both players to be held to all the rules...

# Answer
> 0 votes
Only on local tournaments in friendly atmosphere, with very weak opposition in first rounds, where my risk is minimal and nobody cares. Even if I liked showing respect to some world class player, unexpectedly blundering, maybe offering conditional take back, where he can no longer win the game, you must understand that you are breaking rules and you can hurt other participant seriously with that. That's place where you don't want to be. I won every game easily where I allowed takeback.

# Answer
> 0 votes
I always accept takebacks, always, except in tournaments when the tournament is touch move or touch clock.

---
Tags: rules
---


title: Soundless chess clocks

text:
# Question
Title: Soundless chess clocks
We are trying to organize chess event but the restaurants and coffee shops we asked complain that the sound made by pressing the chess clocks might disturb people.

We could organize the event in a chess club, but coffee shops are better since you can order stuff and have some fun.

We're not going to buy clocks, We're going to borrow whatever chess clubs have for this event. Is it possible to solve this issue?

# Answer
> We are trying to organize chess event but the restaurants and coffee shops we asked complain that the sound made by pressing the chess clocks **might** disturb people.

I believe that your problem is the attitude of the owners rather than any equipment. I would speak with the owner or staff and explain that the sound made isn't loud at all, certainly when compared to the sounds of people talking.

From industrialnoisecontrol.com, 60 decibels is the volume for:

> Conversation in restaurant, office, background music, Air conditioning unit at 100 feet.

Whereas the clocks may be at something like 20 decibels:

> Whisper, rustling leaves
> 5 votes

# Answer
I direct a chess club in a library where many of our members play quick chess. They press the clocks softly, and there is no noise. If one is slamming the timer, then yes, I agree, that could be disturbing. But just let everyone know that that's unacceptable, and that should solve the problem. Also I think there might be a misunderstanding on the shop owners' part. If you demonstrate to them that the clocks can be used quietly, they shouldn't object. Also, some of our players use the timers on their phones, which are absolutely silent. Maybe the owners are just using the sound issue as an excuse for some other reason that they don't want you there
> 3 votes

# Answer
There are some nice apps. For example you can use the "lichess" app. Just silent your phone and have fun. I have never used real chess timers.
> 2 votes

# Answer
I think the easiest solution to the problem is to use a digital clock with capacitive touch sensitive buttons (such as the ZMart clocks, or the Chronos clocks that include the touch sensitive buttons), so there is no mechanical switch to make any noise. I personally don't care for such clocks (with no physical switch I'm often not quite sure I've pressed the button), but they are absolutely silent.
> 0 votes

# Answer
I think the ruckus of players moving pieces and (talking) would be louder than the clocks beeping.

It is literally not an issue, and the idea of being irritated by little sounds is a new modern liberal agenda. It is bull. Almost nobody is naturally irritated unless they have a respectable genetic condition. They just pretend.

There is no issue to solve, just take a clock and demonstrate it to the owner; demonstrate that it wouldn't bother anybody. Another guy said it well; the clock sounds are at 20 decibels while the talking is at 60 decibels. Also only half (or less) will have sounds, right?

If you really need to, most clocks should have a function where you can turn the sound off.
> 0 votes

---
Tags: chess-clocks
---


# Question
Title: Why is 5.c3 the most common move in the Ruy Lopez, Berlin defence, Beverwijk variation?
Disclaimer: I'm a very, very green player.

After the first 4 moves, all of which seem natural given my understanding of basic opening principles (control the center, develop your knights, etc.), I notice 5. c3 is the most common move, according to this database:

```
[fen ""]

1. e4 e5
2. Nf3 Nc6
3. Bb5 Bc5
4. O-O Nf6
5. c3

```

I'm not sure why, though. In particular, it seems really passive. Is it for an eventual d4? If not, what do you see as the reason for this being so common? I would think, e.g., 5. Nc3 would be more common.

# Answer
I'm not really familiar with this variation, but c3 is a typical move in the Ruy Lopez for a couple of reasons: one, which you already mentioned, is to support d4 (and in this variation, d4 has the added benefit of forcing the black bishop to retreat). The other is to open c2 as a retreat for the bishop, which has a tendency to get pushed back by pawns and then threatened with being traded for a knight. In the Ruy Lopez, the b1 knight is often developed via d2.
> 7 votes

# Answer
Even without the bishop on c5, White plays c3 all the time.

Historically speaking, the elixir for e4 players was to try to establish the classical pawn duo on e4 and d4. Therefore, they developed a lot of theory in the king's pawn opening, that all revolve around fighting for this pawn duo.

The approach is, of course, to play c3 so that when you play d4, you're prepared to recapture the pawn with the c3 pawn, instead of with the f3 knight or the queen.

Historically speaking, it has been decided that the Ruy Lopez is the best way to fight for this d4 and e4 pawn duo, because the Ponziani (1. e4 e5 2. Nf3 Nc6 3. c3) runs into some problems after 3...d5, neutralizing the center right away (which Bb5 doesn't allow) (Black has to know some theory, though. There are actually a lot of traps in the Ponziani!).

Now why is this e4 and d4 pawn duo better than say... Nc3? Well, the knight on c3 is actually quite passive. The knight belongs on g3, which is why the Ruy Lopez consists of a very common maneuver, that is, Re1 to prepare Nd2-Nf1-Ng3 (or Ne3!). Furthermore, having a pawn duo for white is always considered to make a difference between having an advantage and being equal.

Lastly, because the bishop is on c5 which it usually doesn't go to (goes on e7 or sometimes g7), the c3-d4 pawn break becomes even more attractive, hitting the bishop with tempo. However, some of the Bc5 lines are quite sharp and so White has to study some theory (it's called the Archangel!), and not always does white play c3-d4, but rather d3 (solidifying e4), followed by Nc3, Bg5, and Nd5. This is usually only when Black plays Bb7, though (and by playing d3, that would shut off a bishop on b7).

Enjoy!

Edit: I forgot to mention that White also plays c3 so that the bishop can retreat to c2.
> 4 votes

---
Tags: opening, 1.e4, ruy-lopez
---


# Question
Title: What are the main tournaments in the chess world?
What are the big events that big players visit? Do every big Tournament has an effect on the players rating?

# Answer
> 2 votes
If you wish to know about tournaments for top players, I would direct you to 2700 chess (scroll down under the list of players).

If you consider a " big tournament" an open tournament with let's say 100 participants (and maybe 1 or 2 of them are top players), then do a search in some comprehensive chess calendar, e.g.: chess-calendar.eu or FIDE's calendar.

---

Not just the biggest tournaments affect player's FIDE rating, almost every small tournament can do that, too (all FIDE needs is some... money).

Therefore the only exceptions I can think of are friendly matches and alternative chess tournaments (Fischer's chess, Basque chess etc.).

---
Tags: rating, tournament
---


title: Deep Blue vs Kasparov - Aftermath

text:
# Question
Title: Deep Blue vs Kasparov - Aftermath
Evaluating 200M positions per second and having a search tree of 20+ moves might not be enough to beat a World Champion if a computer searches in the wrong direction or if it's evaluating positions a human opponent would never consider (either by instinct and/or reasoning). Coding tactics is easy, coding strategy is *hard*.

Was Deep Blue human assisted when it beat Kasparov in 1997? Is there any evidence about that?

Can a commercial software chess game running on a "common machine" beat a chess master nowadays?

# Answer
Game Over: Kasparov and the Machine is a decent enough documentary on the subject. The coverage does kind of imply that Kasparov was grasping at straws a bit. Like a typical World championship match there was a lot of behind the scenes tactics going on from both sides.

My feeling is that you only have to look at the ascent of Anand and other chess players who rely heavily on computers in their training and analysis to realise that, at the time of this match, there was a paradigm shift from human to computer as the dominant chess player.

Addendum:

There's a interesting tidbit in Nate Silver's “The Signal and the Noise: Why So Many Predictions Fail—But Some Don’t.” In it he describes an interview with one of the engineers who worked on Deep Blue:

> Nevertheless, there were some bugs in Deep Blue’s inventory: not many, but a few. Toward the end of my interview with him, \[Murray\] Campbell somewhat mischievously referred to an incident that had occurred toward the end of the first game in their 1997 match with Kasparov. “A bug occurred in the game and it may have made Kasparov misunderstand the capabilities of Deep Blue,” Campbell told me. “He didn’t come up with the theory that the move it played was a bug.” The bug had arisen on the forty-fourth move of their first game against Kasparov; unable to select a move, the program had defaulted to a last-resort fail-safe in which it picked a play completely at random. The bug had been inconsequential, coming late in the game in a position that had already been lost; Campbell and team repaired it the next day. “We had seen it once before, in a test game played earlier in 1997, and thought that it was fixed,” he told me. “Unfortunately there was one case that we had missed.” In fact, the bug was anything but unfortunate for Deep Blue: it was likely what allowed the computer to beat Kasparov. In the popular recounting of Kasparov’s match against Deep Blue, it was the second game in which his problems originated—when he had made the almost unprecedented error of forfeiting a position that he could probably have drawn. But what had inspired Kasparov to commit this mistake? His anxiety over Deep Blue’s forty-fourth move in the first game—the move in which the computer had moved its rook for no apparent purpose. Kasparov had concluded that the counterintuitive play must be a sign of superior intelligence. He had never considered that it was simply a bug.
> 24 votes

# Answer
It isn't hard to find machines/programs rated 2200+ nowadays, so yes machines can beat masters.

Kasparov's comments versus Deep Blue are sour grapes. Kasparov once boasted that a machine could not beat him because he could create and a machine could not. He failed to realize that sufficiently deep tactics are indistinguishable from creation ;-)
> 12 votes

# Answer
Kasparov accused Deep Blue of cheating, but I don't believe there is any evidence about this.

Anything can happen on any day, so yes, a commercial software chess game running on a "common machine" can beat a chess master.
> 6 votes

# Answer
Kasparov did just (beginning of 2017) publish a new book on this topic. He comments on the whole IBM fair play issue in the book.

In the book Kasparov also reflects on why IBM placed Russian speaking security guards at his hotel and why a specific change was made to Deep Blue on the very same morning that the final game was to be played. And exactly a game play change related to the very opening that Kasparov had discussed with his team about the night before the final game.

Se also:
http://www.kasparov.com/deep-thinking-ai/
> 2 votes

---
Tags: engines, history, world-championship, kasparov, human-versus-machine
---


# Question
Title: Why do many players resign from chess in a relative young age? And become coaches or writers instead?
Have they reached their peak rating and find it unmotivating to pursue any further?
Are they lacking financial security?
Are they tired of travelling?

# Answer
A lot of chess players make a living off of chess coaching. You can't make enough money by playing tournaments unless you're like top 100 in the world. Therefore I assume that some people must have to resort to writing books and coaching people in order to make enough money. Considering that they resign at a young age, they must plan this out. On top of that, I would assume that maybe when you combine family life (if you're a father or mother) with coaching, having a small normal job, and a tireness from travelling, then you'll never have time to play at tournaments.

By the way, I would say that no, they haven't reached their peak, that's not why. Just look at Mark Dvoretsky, he is only an IM, but he could definitely be a GM if he wanted. It is because of personal choices, financial reasons, and convenience reasons. Or, maybe they just love teaching but hate playing in serious competitions due to stress. Besides, tournaments can cost tons of money.

Chess is considered the second most stressful sport behind skydiving.
> 2 votes

---
Tags: psychology
---


# Question
Title: Why did Lilienthal resign after (37. Rc1) in Lilienthal vs Botvinnik (USSR Championship, 1945)?
It seems like Lilienthal's **37. Rc1** prevents black from placing his Rook on **Rb1** and give chessmate helped by the black **Nc3**

What is the obvious way to chessmate for black here?

---

**Game:**
Andre Lilienthal vs Mikhail Botvinnik 0-1
USSR Championship (1945), Moscow URS, rd 12, Jun-20

**Link:**
http://www.chessgames.com/perl/chessgame?gid=1032107

# Answer
> 4 votes
White resigned simply because the c3 knight is poison due to a mate in 3 starting with Re1.

Therefore black can just play hxg4 hxg4 then undermine the e5 knight with g5. Notice that the e5 knight gets trapped. There is no way out of both these mating conundrums and these knight trap schenanigans (schevenigen lol!)

Here is the diagram if we give White a free move. That's right, Black had the move in this game and he will smash with hxg4 followed by trapping the knight on e5 (after g5), but even if White moves first, Black is still smashing!!!

```

[FEN "8/ppk3p1/1r6/3pN2p/2p2PP1/2n1r2P/P2R4/K1R5 w - - 0 0"]

1.Rxc3 (1.Rdc2 (1.gxh5 Re2 2.Rxe2 Nxe2 3.Rc2 Nxf4 4.h4 Kd6) 1...Ne2 2.Rf1 (2.Re1? Nd4) h4
3.g5 Re4) 1...Re1+ 2.Rd1 Rxd1+ 3.Rc1 Rxc1#

```

By the way, I checked this position with a computer (Stockfish 8, depth 28) just to make sure I was right, and the initial position here before Rxc3 scores as -5.4 (if Black moves as in the game) and -3.2 if White moves here. Now here is the position if it is Black to move, as in the game.

```

[FEN "8/ppk3p1/1r6/3pN2p/2p2PP1/2n1r2P/P2R4/K1R5 b - - 0 0"]

1...hxg4 2.Nxg4 (2.hxg4 g5 3.Nf7 (3.Nxc4 dxc4 4.Rdc2 gxf4 5.Rxc3 Rxc3 6.Rxc3 Kd6
7.Rxc4 Ke5 8.Ra4 f3) 3...gxf4 4.Ng5 Rg6) 2...Re2 3.Rxe2 Nxe2 4.Re1 Nxf4 5.Rh1
(5.Rf1 Nxh3) 5...c3 6.a3 d4

```

If White doesn't play right, then Black just immediately wins material or mates. If White plays right, then Black gets a winning rook endgame because of his massive advantage in pawns.

At the end of the day, he probably resigned 20 or so minutes after making that move just based off the endgame. Remember, Mikhail Botvinnik was like the most heavy duty Russian chess dude out there.

Chess was serious business to him and the Russians trained in endgames more than other people did. Botvinnik actually tackled a line of the Semi-Slav (a line of the Semi-Slav Botvinnik I think??) for 100 hours worth of preparation! These top players gave Chess their 110%.

---
Tags: resigning, botvinnik, lilienthal
---


# Question
Title: What are good defenses of black King with Bishop on f8 or g7?
As black, I like to return my dark square Bishop to the King after castling short. I want to develop my skills in defending that position. In what openings does it occur?

And how should one in general search for such a nameless(?) concept or strategy? Is there for example a database where one can search for Bf8 in the ten first moves?

# Answer
There are a lot of openings where Black fianchettos his king's bishop, and it ends up on g7. Versus 1. d4 you have the King's Indian Defense and the Grünfeld Defense; if White opens 1. e4 you can respond with the Pirc Defense. The Modern Defense is usable against both.

*Without* playing g6, Black has to move his rook on f8 (after castling short) and retreat the bishop to f8. That's far less common, though there are some (side)lines in the Sicilian and the Ruy Lopez where this happens.
> 5 votes

# Answer
The Ruy Lopez and the Philidor have variations with this move so the rook can put pressure on the e pawn. Since the plan is to restrain and attack the e pawn, these maneuvers often become a fianchetto.

Chessbase does allow a search like this. It also has a search for just some of the pieces, that is, you can place a king of g8 and a bishop on f8, and the program will search all games which has at least that configuration. I'm sure that various free databases, such as SCID, chesspad, x/winboard, and arena, have this pattern search.
> 3 votes

# Answer
Good defenses?

Against e4, well there are lines such as the sicilian hyperaccelerated dragon, the accelerated dragon, and the traditional dragon. There is also the modern 1...g6 which is usually okay, and also the pirc which is suboptimal. As for systems where the bishop retreats, you can commonly find that in the Breyer System (a line in the Ruy Lopez). In the breyer as well as other lines in the Ruy Lopez, Black plays Re8 followed by Bf8, g6, and Bg7.

If you want a solid defending position, then you should try the Breyer system. Look it up )). Just know that you may not reach it too often, but the way that Black plays into it is always 'good', if that makes sense. Otherwise try the pirc or the traditional dragon maybe, both are actually quite fun to defend. But objectively the Breyer is one of the best systems for black; it is extremely theoretically healthy.

Against d4, both the Grunfeld and King's Indian setups are good for what you're looking for. I play the Grunfeld by the way.

By the way, there is a line in the English (and also the larsens! 1. b3) where Black retreats the bishop to f8, but doesn't fianchetto via g6.

It goes 1. c4 e5 2. Nc3 Nf6 3. g3 d5 4. cxd5 Nxd5 5. Bg2 Nb6 6. Nf3 Nc6 7. 0-0 Be7 8. d3 0-0 9. a3 Re8! (preparing to guard e5) 10. b4 Bf8. I enjoy this position for Black too.
> 1 votes

---
Tags: opening, castling, bishops, defense
---


# Question
Title: What if we downloaded a gigantic database of chess games into our brains (intelligence downloads)?
If we downloaded a gigantic database of chess games into our brains (intelligence downloads), then would we play at a stronger level than the world's leading top players?

What about if we downloaded a 7-piece tablebase into our heads?

And also I was thinking the size of the game database would be 6.5 million games, and all grandmaster games or at least above 2400.

# Answer
> 3 votes
If that database contained purely grandmaster games, and we were fast enough to process all of that information, then you could technically replicate the moves of any grandmaster and become *equal* to their skill level. However, if faced with a board layout not in the database, you would have to use your own intuition. That, unfortunately, must be learnt and cannot be downloaded.

If you downloaded games from chess computers too, you could play at a higher level than any human, however new board states would again throw you off since you would have to process the board yourself and not rely on the database.

So I guess the answer is that if you downloaded a database of all grandmaster and computer games you could theoretically beat any grandmaster as long as you repeat a game in which the side you are playing as won. Any divergence into a new line will make the database obselete.

As for the tablebase, you would have to hold your ground against your opponent until there were 7 pieces left, and then you would be able to spot the best move for the rest of the game. The issue here is that with 7 pieces left, most grandmasters are nearly flawless in their endgames anyway, and unless you enter the endgame with a small advantage you will be pretty much equal, even with machine skill.

# Answer
> 3 votes
It would hardly help, because **chess is not a game of knowledge**. It's a game of skill. It wouldn't be much different from "downloading" video of all football games ever and expecting to play like Messi.

To play strong chess, you need to be able to find the best move in a position you've never seen before, that usually has never been played before.

Yes, pattern recognition is a big part of it -- but you'll still need to know *why* those patterns work, *why* moves were played and others weren't, and be apply to apply that knowledge to new positions. Just knowing the old games instead of having them in a database isn't that much help. And there are still lots of positions where pattern recognition *isn't* the important thing, but rather exact calculation.

Tablebases are different matter, because they contain *everything* when the number of pieces is small enough, and the moves they contain are perfect. If this player reaches a winning position that is in the database, he'll always win it. That's much better than human players manage. But he'll have to reach those positions first...

# Answer
> 2 votes
I don't think it'll help, unless you download the Stockfish engine (but not the database). You can't win a game by just checking the database, you'll need the understand the moves. There's no point with a 7-men tablebase if you miss a simple tactic in a new position not in the database.

I'm convinced I can defeat a FIDE 1400 player, even if the player is allowed to search the database during the game. I'm happy to allow my opponent unlimited access to 7-men tablebase. That wouldn't make any difference.

---
Tags: database, psychology, computer-chess
---


# Question
Title: (Rook + Knight vs Rook) vs (Rook + Bishop vs Rook)?
Despite these endings being theoretical draws, I have heard that people play on because of significant winning chances. My question is which one has more chances? I would guess the bishop, but I do not know. Is it difficult to draw against the rook and knight?

# Answer
**TL;DR:** Rook + Bishop offers significantly more winning chances against a lone Rook (38%) than Rook + Knight (only a few %).

**Full answer:**

'Secrets of Pawnless Endings' by John Nunn mentions the following about the ending with the Knight:

> \[the stronger side\] has far fewer winning chances than in the ending of R+B v R and in practice the ending is often agreed drawn immediately. Top-level wins are very rare, but there was one famous example in J.Polgar-Kasparov, Dos Hermanas 1996 being one of the exceptions.

The chapter about R+B v R mentions 74 games of which 28 (38%) were won by the stronger side.

The book I already mentioned, and 'Fundamental Chess Endings' by Lamprecht and Müller, cover these endings. For the Bishop ending, they both explain the main defensive techniques, the so-called Cochrane defense and the Second Rank defense, and some key positions (discovered by Philidor in the 18th century already) which can be won by the stronger side, e.g. this one.

The endgame with the Knight is easier to hold in general. The defending side needs to prevent their King being forced to the edge; if that does happen, the chances of winning are actually greater than with the Bishop. An advantage for the defending side is that the Knight is worse in protecting its own King from checks by the defending Rook. If the defending King is confined to the edge, his rook should either pin the Knight or give annoying checks; this resembles the Cochrane defense in the Bishop ending. Some winning positions were published by Centurini in the 19th century.

In general, endgame databases are very helpful, at least for analyzing winning positions. For draws, they are trickier to use, because they don't tell you how *difficult* it is to hold a certain position. Especially the Bishop ending contains many 'marginal' positions which can only be held with secure play.
> 8 votes

---
Tags: rook-and-minor-endgame
---


# Question
Title: Stockfish evaluation of a position from PGN
I am trying to get Stockfish's evaluation of a board position(which is in PGN format) using command line.
I know it accepts board position in FEN format, but is there any way i can provide PGN format?
If no, how can i convert PGN format to FEN?
Is there any tool in Python which can help me out?

# Answer
Yes there are easy ways to do this. I'm going to briefly show you one quick way of doing it in python, using the python-chess module. If the in-code comments are not enough, feel free to ask for clarifications or possible extensions of the code:

To showcase a working example, I've taken a game between Adams and Kasparov, you can download the PGN from the hyperlink. And our engine is the latest Stockfish available taken from the official website.

Lets call it `PGNeval.py`:

```
import chess
import chess.uci
import chess.pgn
import sys

arguments = sys.argv
pgnfilename = str(arguments[1])

#Read pgn file:
with open(pgnfilename) as f:
    game = chess.pgn.read_game(f)

#Go to the end of the game and create a chess.Board() from it:
game = game.end()
board = game.board()

#So if you want, here's also your PGN to FEN conversion:
print 'FEN of the last position of the game: ', board.fen()

#or if you want to loop over all game nodes:
#while not game.is_end():
    #node = game.variations[0]
    #board = game.board() #print the board if you want, to make sure
    #game = node

#Now we have our board ready, load your engine:
handler = chess.uci.InfoHandler()
engine = chess.uci.popen_engine('...\stockfish_8_x64') #give correct address of your engine here
engine.info_handlers.append(handler)

#give your position to the engine:
engine.position(board)

#Set your evaluation time, in ms:
evaltime = 5000 #so 5 seconds
evaluation = engine.go(movetime=evaltime)

#print best move, evaluation and mainline:
print 'best move: ', board.san(evaluation[0])
print 'evaluation value: ', handler.info["score"][1].cp/100.0
print 'Corresponding line: ', board.variation_san(handler.info["pv"][1])

```

Lets test it with the aformentioned game PGN, our command is:

`python PGNeval.py adams_kasparov_2005.pgn`

And here's the output I get:

`FEN of the last position of the game: br3r2/5ppk/p2pp3/4b1BP/N3P3/q4P2/1PnQB3/1K4RR w - - 4 27
best move: Qxc2
evaluation value: -10.87
Corresponding line: 27. Qxc2 Rfc8`
> 11 votes

---
Tags: analysis, stockfish, programming, pgn, fen
---


# Question
Title: Why doesn't 1.fxe4 Nf6 work for black in this puzzle?
I was solving puzzles and I failed this one. The correct answer was `fxe4 fxe4 Bxh5+`. Why can the knight not just move to `f6` and be safe there?

`fxe4 Nf6 exd5 fxd5` is in my opinion more preferable for black.

```
 [Title "1...Nf6?"]
 [fen "rnbqk2r/ppp3pp/3b4/3p1p1n/3Pp3/1P2PPP1/P1P1B2P/RNBQK1NR w KQkq - 0 1"]

```

# Answer
> 6 votes
Because after `Nf6, e5` is a double attack on the `d6` bishop and the `f6` knight.

The puzzle aside, given that black's dropping the piece anyway, may as well go for something practical, like `Nxg3, hxg3, Bxg3+...` and take 2 pawns for the piece, with some positional compensation as the king will be misplaced, but objectively white should of course be easily winning.

```
 [Title "Puzzle"]
 [fen "rnbqk2r/ppp3pp/3b4/3p1p1n/3Pp3/1P2PPP1/P1P1B2P/RNBQK1NR w KQkq - 0 1"]

 1.fxe4 Nf6 (1...fxe4 2.Bxh5+) (1...Nxg3 2.hxg3 Bxg3+) 2.e5

```

---
Tags: analysis, puzzles
---


# Question
Title: What is the minimum number of pieces needed in a chess set to account for all possible promoted pieces?
How many pieces would be needed in a chess set where all possibilities for promoted pieces are included if pawns are no longer used after they promote?

# Answer
Let's count.

### Starting set

* 2 rooks
* 2 bishops
* 2 knights
* 1 queen
* 1 king
* (8 pawns)

### Max promotions

* 8 rooks
* 8 bishops
* 8 knights
* 8 queens

### Total

In total you would need 40 pieces and 8 pawns for each color, so 96 units for black and white together.

Edited to bullet format to "look" better.
> 7 votes

---
Tags: pawn-promotion, pieces, mathematics, chess-set
---


title: Why is it called the Max Lange attack?

text:
# Question
Title: Why is it called the Max Lange attack?
Why is it called the *Max* Lange attack and not simply the Lange attack? After all, we don't have openings called the Richard Reti opening or the Wilhelm Steinitz defense or the Frank Marshall attack. Is the Max Lange the only opening with a first and last name?

# Answer
Well, they don't have an explicit protocol on whether to use the first name, the last name, or both the first and last name. Though admittedly, the Lange Attack sounds more right than the Max Lange attack.

There is a completely different story for how an opening gets its name. There are a couple openings that are named after people that didn't even play the opening or come up with the opening itself. Furthermore, there are openings named after animals or whatever; the Sicilian dragon, the Halloween gambit, the English opening, the French defense, the Hedgehog, the King's gambit, etc.

It might be based on the individual. They try to come up with a formal name of a variation based on the person's name, but to some people, it is more formal to use only the last name or the other way around (Grandmaster Tarjan instead of Grandmaster James or Grandmaster James Tarjan). On top of that, if you are lesser known or not famous, then it is considered more formal to use both the first and last name.

You have the Ruy Lopez, but not many other openings that use the first name. It is likely a result of the guy's preference. Again, an individual story for every opening, and it is cultural and normal to use only the last name, but there is ought to be a line that uses the first and last name too.
> 1 votes

---
Tags: opening, terminology
---


# Question
Title: Why an analyser labels this move as a blunder?
On the picture, you see the move that was offered by the analyzer. My move was Na5. Forking the Queen and the bishop, so I can negate white's attack on f7 and defending the undefended pawn b7, so the queen can not take it. However, the analyzer labels it as a blunder and offers Nd4. Why it's better? Why is my turn a blunder, where can I lose here material?

# Answer
> 7 votes
1...Na5 isn't a losing blunder, Black definitely has a much better position after 1...Na5 2.Qc3 Nxc4 3.Qxc4 Nxd5. Black's lead in development and White's weak position (e.g. the g3 square and the king on e1) should be decisive.

However, 1...Nd4 is a even stronger move because the c2 square is under attack and can't be defended. White can resign immediately after 1...Nd4, whereas White could resist a bit longer after 1...Na5.

You had a winning position, but you weren't able to find the most decisive killing move. Whether this was a "blunder" is debatable.

# Answer
> 7 votes
Your move 1...Na5 is a blunder because there was an opportunity to win material.

The suggestion 1...Nd4 is best because you win a rook, e.g. 1...Nd4 2.Qxb7 Nxc2+ 3.Kf1 Nxa1

# Answer
> 2 votes
In addition to other answers, applications consider a move blunder when there is a much better move. By much, I mean like 150-200 centipawns. (100 centipawn equals to 1 pawn)

# Answer
> 1 votes
A blunder doesn't mean you're worse. If you're white and you play a move that goes from +10 to +7, then it will classify that move as a blunder. Same for if you're +3 and your move makes you +1.5; it will call it a blunder.

Na5 only wins a bishop (and a better position) for a knight and Nd4 wins a pawn with a K+R fork by attacking the queen.

---
Tags: analysis, strategy
---


# Question
Title: After analyzing games with a coach should we play them again on the board?
I analyze my tournament games with my chess coach on the computer and in the end I have a PGN file which contains all the variations, mistakes, and tactics i missed. The question is am i suppose to play the game all over again on the board trying all the variations etc, or just studying them on the computer screen enough?

# Answer
It is always a good habit of moving pieces over the board. The best players in the world practice it, and they also recommend it. Sometimes, I can understand that in a busy world you may not have the time and space to occupy yourself and arrange the pieces OTB.

As far as games are concerned, it depends whether you are learning a specific opening or a variation, then it always useful that you practice your winning games or the games where you have learnt a lot. GM Igor Smirnov says that before you play a tournament, you must have a look into your own games where you had a good win. It not only exuberates your confidence but gives you a strong determination to win the game. Kasparov also says that you must memorize some of the games related to a specific opening which you play. It helps you to remember patterns and best moves in a particular opening.
> 1 votes

# Answer
I agree that moving the physical pieces impresses upon the mind more thoroughly than by electronic means. We think and conceptualize in 3 dimensions, so it is only beneficial you should learn and study in the same manner. I know I get much more out of reviewing master games on a physical set than pumping through them on my computer in ChessBase. It takes longer, but it's not a race.

The wrong thing would be to think you learned everything from that one session and file the analysis away. Come back and review it frequently and you will make more discoveries.
> 1 votes

# Answer
Once you have thoroughly analyzed your game, it completely depends on your preferences.

What I usually do is first analyze it on my own on the chess board, trying to come up with the critical positions and evaluating the position on my own. I then use a computer to check the analysis, specifically if the variations I thought as possible replies or alternative options were sound. Finally, I play the game again over the board and share my analysis with my coach.

While the very last option is not indispensable since you have already done the work previously, I found it useful: exposing one's ideas help to clarify them and the critical evaluation of the coach and the rest of the students in the class usually brings up alternative interesting variations.
> 0 votes

# Answer
Number one, you should ask your coach if you haven't :).

Secondly, I think it is a really good idea to go over the PGNs if you approach it as if it were an OTB game.

I say load the PGN and pretend you're playing one side as if it were a long OTB game. Then after moves have been made, read the annotations and back it up with engine analysis. I think this is good enough. You don't have to memorize anything unless it is an opening trap or an opening line. Otherwise, if it is deep in the middlegame, then you don't have to memorize unless u want to build a game database and store it in your head, studied, all by memory, but thats debatable and probably not super helpful unless you've reached the position a lot and you need a recipe. Anyway that's a topic for a different thread.

Yeah, just read through it, study the chess board, play it like OTB, and most importantly take it slowly.
> 0 votes

---
Tags: engines, analysis, learning, tournament
---


title: Valid PGN variations?

text:
# Question
Title: Valid PGN variations?
I've received the following PGN text that I suspect invalid:

```
8.f4
    {0.22/17 0 last book move}
8...e5
    ( 8...b5
       ( 8...Qb6
           ( 8...Qc7 9.a3

```

What exactly the position the moves come from is unimportant. Please note the PGN text has **four** 8th Black moves (`8...e5`, `8...b5`, `8...Qb6`, `8..Qc7`), and two of them (`8...Qb6` and `8..Qc7`) are **under** `8..b5`.

I suspect this is a mistake because the alternative Black moves should be represented like the diagram:

I generated the diagram with the Scid vs PC software. Please note the alternative Black moves are written in parallel. For example, `8...Qb6` and `8..Qc7` **are not** included inside the `8...b5` bracket.

Some softwares (e.g. Scid) are able to read it, but some fail (e.g. ChessX). My own PGN implementation can't handle the nested structure.

**Q**: Is the PGN text I posted valid? What does the PGN specification say?

**EDITED:**

The game is here. Open the game in a text editor, and you will see the following:

```
e5
    { 0.22/17 237 }
    ( 8...b5
        ( 8...Qb6
            ( 8...Qc7 9.a3

```

# Answer
> 7 votes
Good question. This nested notation (also called: recursive annotation variation, RAV for short) is uncommon but valid\[\*\]. In the example you provide, most online PGN readers have no problem parsing and accounting for all the variations and subvariations. So the way to read it is as follows: the nested structure is composed of independent variations, only if there's a closing parenthesis then it is an actual subvariation (so a specific branch out of a previous variation). An example from your PGN: `8... Qc7` is a variation, `(9.Qe1...)` is a subvariation and `(10.Bf3...)` is a subsubvariation. So the nesting is: `(8... Qc7 (subvariation (subsubvar...) ))`.

Various libraries/modules may not have a built-in parsing system to tackle such PGN structure\[\**\], so you may have to extend this on your own. For further reading, Tim Harding also explains the nested notation and its lack of implementation rather more succinctly here, I briefly quote:

> An RAV (Recursive Annotation Variation) is a sequence of movetext containing one or more moves enclosed in parentheses. An RAV is used to represent an alternative variation. The alternate move sequence given by an RAV is one that may be legally played by first unplaying the move that appears immediately prior to the RAV. Because the RAV is a recursive construct, it may be nested. ...
>
> Some software may find it hard to handle nested variations too. Palview3 was the first freely-available PGN software, that I am aware of, that could create with variations in HTML pages, and it is restricted to two levels of notes (three levels counting the actual moves of the game). For most purposes, this is sufficient. Most Java Viewers can only show the actually played moves, except as text notes, but playing through a Palview3 web page is close to the experience of playing it through in a program like ChessBase: a major advance for chess webmasters.

That said, nowadays, there are various online pgn-readers that already do this, some examples (so if you paste your PGN onto either of these, it can be fully read and displayed).

You may find additional information on the standards of PGN here. I will get back to you if I find other potentially useful elements.

---

\[\*\]: just to make sure, I also quickly parsed the text to make sure all parentheses are properly closed.

\[\**\]: for example, the `chess.pgn.read_game` method from `python-chess` fails to fully read this PGN, it only sees the main variation upto move `8... e5.`

---
Tags: pgn
---


title: Is the Scandinavian Defence inferior?

text:
# Question
Title: Is the Scandinavian Defence inferior?
As Black, I have never played the Scandinavian Defence, nor have I ever liked the Center Game for White. It seems like `1. e4 d5` wastes valuable time after `2. exd5 Qxd5 3. Nc3` and Black's Queen must flee, while White can comfortably develop:

The same drawback goes to White in the Center Game:

```
[FEN ""]
1. e4 e5. 2. d4 exd4 3. Qxd4 Nc6

```

But the opening, notwithstanding, appears to be still popular, and online players have often played it against me. Is there some redeeming virtue that I'm missing in this defence?

# Answer
> 15 votes
Here are a few reasons one may take up the defense:

* Despite having the Queen kicked by the Knight, the Queen is in no real danger of being trapped, its most common escape locations being to a5 and d6.
* Black's pawn structure is solid, in similar ways to the Caro-Kann.
* The number of lines Black needs to know are fairly limited, this makes it an easy defense to get into.
* It's not played very often, so the Black player will likely have more familiarity with the positions than White.
* Black is able to develop all the pieces and castle in relative safety; notable is the ability to develop with the Bishop on c8 before `...e6` is played.

# Answer
> 10 votes
Seems to me some players have a critical opinion about the Scandi mostly based on the fact that White gains time on the queen with Nc3. Actually, White only recovers the tempo "lost" on his second move (exd5). Someone even called it "theoretically inferior" based on the first few moves. The Scandi is perfectly playable, and there are several strong GMs playing it regularly. Tiviakov, Kramnik, Ivanchuk, Karpov on his older days just to name a few, and even Carlsen has tried it out. The Scandinavian Defence - especially the 3...Qd6 variation - equalizes in almost every possible line against 1.e4. The "problem" (if there is one), is not the irrelevant Nc3 threatens queen discussion, but the fact that it can be difficult to win with lots of games with Black. At amateur level this is hardly a problem, because most players with White doesn't have a clue about how to play against the Scandi. At higher levels, the main line is :

1. e4 d5 2.exd5 Qxd5 3.Nc3 Qd6 4.d4 Nf6 5.Nf3 c6 (also a6 is played, and GM Kovalenko's aggressive Bg4). Then only 6.Ne5 puts any pressure on Black. Earlier also 6.g3 was considered strong, but it has been well neutralized by Black thanks to the efforts of GMs Tiviakov and Kontronias.

After 6.Ne5 play goes: 6...Nbd7 and White has three main tries:

7. f4 (Shirov's idea) 7.Bf4 7.Nc4

The Bf4 variation is not a problem anymore. Black equalizes quite easy. 7.f4 and 7.Nc4 is more challenging, but Black has found ways to maintain the balance and the theory of these lines are quite heavily developed. Playing Scandi (at least on a higher level) requires knowledge of these lines, and how to handle these quite complex middlegames. It is not enough to know just the opening lines of the scandi, it also important to know these middlegames, and you will need strong endgame abilities to win (or draw) these positions - both as White and Black. This is the "problem" of the Scandinavian (and in all other openings I guess).

Wish you all best of luck playing both sides of the Scandiavian Defence.

# Answer
> 5 votes
I usually play the `2...Nf6` line. I play it because it is forcing and I can focus on one defense, and white usually isn't as prepared for it. It gives black a lot of play and tactical choices. It's a fun line.

# Answer
> 3 votes
I'm a Candidate FIDE Master and I've tried the Scandinavian Defence, and Modern Variation, in the last 2 years. Against weaker opposition my results were very good. Black equalises easily, and quickly, and has very active pieces. The c4 move by white, taking the centre, is hardly a serious problem for the prepared player. After all, many defences concede the centre to white, only to counterattack it later. It is a concept introduced to chess 150 years ago by the Hypermodern School in chess, of which, Aron Nimzovitch was the chief exponent. Defences of this type are the French, the Pirc, the Modern Defence, the Alekhine Defence, and are all played by strong European GMs.

To say that the Scandinavian defence is inferior is laughable,but there is a small problem,in my opinion,to be honest.If you need to win on a specific game with black and face a good opponent,if as white they play very solidly,it is hard to obtain a promising position and the majority of games at higher level end up in draws. Black gets winning chances only if the players with white press too much for the win,underestimating the position.

# Answer
> -1 votes
The Scandinavian defense is theoretically inferior because White will gain time with his actual, and potential threats to chase the queen. Unlike the Scotch game, the threats against the queen are real, because *no* pairs of knights have been exchanged, and only one pair of pawns.

But it takes very accurate play by White to realize this advantage. The black queen can be placed aggressively at a5, which can cause White some discomfort. Hence, it popularity in an online or club game, where mediocre (White) players abound.

---
Tags: opening, strategy, scandinavian-defense
---


title: The Black knight challenge

text:
# Question
Title: The Black knight challenge
```
[FEN "8/8/8/8/8/pNnbPPpN/RBppPbrP/pkKPrqQR b - - 0 1"]

```

I was introduced to a challenge a few weeks ago with the above position. The challenge is to move the Black Knight such that it must always be three squares in the third row from the right, the point is to capture *all* pieces with the Black Knight. The order of the other pieces doesn't matter.

While an answer is awesome, what I'm mainly interested in is, is this really a thing?

# Answer
> 5 votes
As @Glorfindel pointed out, this is a knight's tour.

One sequence is Nc3-a2-c1-b3-a1-c2-a3-b1-d2-f3-h2-f1-e3-g2-e1-d3-b2-d1-f2-h3-g1-e2-g3-h1.

```
[FEN "8/8/8/8/8/pNnbPPpN/RBppPbrP/pkKPrqQR b - - 0 1"]

1... Nxa2 2. null Nxc1 3. null Nxb3 4. null Nxa1 5. null Nxc2 6. null Nxa3 7. null Nxb1 8. null Nxd2 9. null Nxf3 10. null Nxh2 11. null Nxf1 12. null Nxe3 13. null Nxg2 14. null Nxe1 15. null Nxd3 16. null Nxb2 17. null Nxd1 18. null Nxf2 19. null Nxh3 20. null Nxg1 21. null Nxe2 22. null Nxg3 23. null Nxh1

```

How did I create the sequence? I used Warnsdorff’s Rule:

> Always move to an adjacent, unvisited square with minimal degree.

Where the degree is:

> the number of unvisited squares that are adjacent to a given square

In the case of ties, I calculated ahead and made sure that the knight didn't get stuck.

---
Tags: problems, knights, captures
---


# Question
Title: Did the Danish philosopher Soren Kierkegaard play chess?
The danish existentialist philosopher Soren Kierkegaard lived from 1813 to 1855.

He writes in one of his journals (21st of May 1839):

**Original Danish**

> Jeg lever i denne Tid omtrent som en Brik i Schakspil maa være tilmode, naar Modspilleren siger: den Brik kan ikke røres – som en ørkesløs Tilskuer, da min Tid endnu ikke er kommen.

**Translation by google:**

> I live at this time just like a piece of chess must be, Allowing the opponent to say: that piece cannot be moved - like an idle spectator, because my time has not yet come

**Alternative translation:**

> I feel as if I were a piece in a game of chess, when my oppenent says of it:That piece cannot be moved! like a useless bystander, since my time has not yet come.

# Answer
> 4 votes
> Did the Danish philosopher Soren Kierkegaard play chess?

The answer is a resounding **maybe**.

Firstly, he has no games established in Fritz database. Of course this doesn't mean he didn't play chess, just that there isn't evidence recorded in the database.

**However** it must be remembered that chess was invented in the 6th century and is one of the most popular and famous board games of all time. It is reasonable to assume that he either played casually at least once or knew enough about the game to inform his writing.

---
Tags: history
---


title: Symmetries in chess

text:
# Question
Title: Symmetries in chess
The same games of chess could be played if:

* white and black squares were swapped (i.e. the board rotated by 90 degrees)

or

* king and queen were swapped in the starting position (i.e. white/black kings on d1/d8 and white/black queen on e1/e8)

or

* black was allowed to start the game

Are there any other transformations, which leave the game the same (I think not)?

What is the origin of the current board orientation and king/queen position and first move for white?

Has anybody studied the effect of such transformation on the play? For instance:

* How much worse would an experienced player play?
* Would there be a preference for different kind of openings or trading pieces differently? For instance I could imagine that if the board was rotated 90 degrees (change of square color) this could change play because say a black bishop on a dark square has different contrast than a black bishop on a light square. Similarly, if king and queen were swapped, this could affect play as people are right or left handed.

# Answer
> 2 votes
The only symmetries that leave the game unchanged are rotations, reflections and central inversion.

There are 2 reflections (vertical being swapping king and queen, horizontal being black moves first) and 4 non-trivial rotations (90, 180, 270 and 360 degrees). Doing nothing (i.e. a rotation of 0) is the group theory identity element.

The board can also be centrally inverted. Think of having a double sided board that you flip over. So a1 becomes h8, a8 becomes h1 etc.

If you are interested in studying symmetry in a mathematical context, please investigate group theory.

# Answer
> 1 votes
Bad\_Bishop forgot the third reflection, if the board was upside-down, the game would remain the same..

In the beginning, there was only a grid, no colored squares. The blackening of alternating squares was probably introduced to help see the legal diagonal movements.

The story I heard for first move was giving white the first-move advantage as black was thought to be a lucky color at the time. I assume black and white were used at they were the easiest colors to produce.

As a fairly strong player, altering the color(s) or flipping horizontally would make no difference. Although having a neon set would bother me, but not alter my chess ability. Another problem is a great variance in the piece shape. You can't just make the queen look like (that girl from Avatar) and expect me to treat her like that piece. Just to exaggerate this point, switch the king and queen pieces and see how many times you revert them back to their originals.

---
Tags: chess-variants, psychology, chessboards
---


title: How to create a useful ECO list?

text:
# Question
Title: How to create a useful ECO list?
I am using SCID; the built-in ECO list is very incomplete and sometimes just weird. The *Caro-Kann: Accelerated Panov Attack* for example is called *Caro-Kann: English Variation*, the *Carls-Botvinnik Defense* hasn't even a name, and many sub-variations are just missing.

So I want to build my own list to use it in SCID.

I like the lichess opening list, but it is based on FEN positions, not on moves, and SCID needs the latter. I looked at the related questions here, and searched on Google, but couldn't find a good text file with moves and correct opening names.

How should I proceed? Maybe there is already such a file and I just haven't found it, or I can use FEN positions in SCID instead of moves?

# Answer
> 1 votes
I maintain one here that you might like to take a look at to see if it is any use for your purposes:

PGN for ECO descriptions with moves

# Answer
> 1 votes
I have created this list, but I'm not sure how well it matches your naming convention: http://cricketchess.pcriot.com/opg/

As a programmer, I can tell you it is very difficult to match an opening to PGN but much easier to match it to a FEN. In the case of the Caro-Kann, Accelerated Panov (and other openings as well), it is worthy to note that the opening goes by other names: https://en.wikipedia.org/wiki/Caro-Kann\_Defence#Other\_lines (B10, Modern; English Variation, Accelerated Panov: 1.e4 c6 2.c4).

I found that opening also called "Caro-Kann, Anti-Caro-Kann" for instance in my Android app.

---
Tags: scid, eco
---


# Question
Title: What is the problem with my negamax implementation?
I am currently attempting to make a basic chess engine in Python (Learning some basic concepts), but for some reason the engine is suicidal and does not detect the scholars mate. I am using python-chess for the board because I am lazy, but I think the issue is my implementation of negamax? I've read on chessprogramming wiki but still can't figure out the issue.

Here is the code on GitHub: https://github.com/AggressiveBee15/LousyEngine

# Answer
> 1 votes
I didn't run your code, but by just looking:

* You should return the score when `score >= beta`. This is consistent to Wikipedia:

Note when alpha \>= beta, Wikipedia returns the score, not beta.

* Your code doesn't detect checkmate? I don't see how your engine can report Scholar mate without detecting checkmate.
* Minor issue. The condition should be `>=` not `>`, but that shouldn't change anything.
* What outputs did you get from: `print('New good move ...`?

---
Tags: engines, programming
---


# Question
Title: Is always possible to win King + Queen vs. King + Rook?
Does every situation (except where the Queen team gets mated or the Queen is captured immediately) result in a win for the Queen team? Or can the Rook team, by perfect play, force a stalemate?

# Answer
> 17 votes
Mate is always possible, except in the cases you've outlined already. From Wikipedia:

> A queen wins against a lone rook, unless there is an immediate draw by stalemate or due to perpetual check (Nunn 2002a:49) (or if the rook or king can immediately capture the queen). ... With perfect play, in the worst winning position, the queen can win the rook or checkmate within 31 moves (Müller & Lamprecht 2001:400).

---
Tags: endgame, rooks, queens
---


# Question
Title: Estimating probability of player playing move in the opening
For position you never played, book probability is perfectly fine for me. The question starts when you already played position x-times. I'm looking for function that will update book probabilities with your style. Obviously if you play 1.d4 in 97 games out of 100 games, probability of playing 1.e4 runs close to 0%. On the other hand, if you played some late position just once, it's nowhere close to 100% you will repeat the move. I could probably make some workaround myself, but this looks like problem data scientists must have already solved, as it is applicable to virtually any discipline where you want to predict someone's behavior.

**Edit: I think there should be one parameter \<0;1\> measuring how seriously we take book probabilities and how seriously we take players games. With one extreme being ignoring book and one being ignoring player's games.**

# Answer
Intuitively we should look at the player's games for early moves and book moves for later. This is because as we get further in a game, the number of possibilities increases, therefore the sample size of player games decreases. In this scheme, we are assuming that the player in question behaves as the average player does in the long run given the positions they usually seek from the opening.

You could use a rule of using the player's games if there are more than 5 to use, and using other players games otherwise.
> 2 votes

---
Tags: opening, programming, mathematics
---


# Question
Title: (4 Queens + 3 Pawns) vs (Entire Standard Army)
My club has recently been playing the variant Etchessera. For those unfamiliar, this variant allows you to build an army consisting of a King and up to 39 points worth of pieces according to the following system:

* Pawn - 1pt
* Knight - 3pt
* Bishop - 3pt
* Rook - 5pt
* Queen - 9pt

While I realize that the relative point values are often listed differently, and can change based upon what other pieces remain, we were wondering if there should be a clear winner between the standard chess army and one consisting of 4 queens and 3 pawns.

Through our own games, the match-up appears to still be about equal provided the classic army plays defensive openings and forces a few trades. However, my club is a very small sample size and I was looking to see if this has ever been explored elsewhere.

# Answer
A clarifying comment says "Pawns can be placed in any of the first 3 rows. Any other piece must be placed in the back row. White moves first unless black used less points to construct their army." So the position I gave earlier doesn't work, but since Black is allowed to move first with fewer than 39 points there's still a forced win:

```
[FEN "1b1qkqq1/8/8/8/8/8/PPPPPPPP/RNBQKBNR b - - 0 0"]

1. Qxf2+ Kxf2
2. Qh4+ g3
3. Qgxg3+ hxg3
4. Qxg3#

```
> 9 votes

# Answer
In the specific position you show, I can well believe that the classical army has an advantage: I've read that a second Queen tends to be redundant and thus worth less than the first, so I'd expect a third and fourth Queen to continue the pattern, assuming that the opponent's King is not in immediate danger. But if you can array your fantasy-draft army anywhere you want in the first few rows you can win by force even with fewer than 39 points:

```
[FEN "q3qr1k/b4q2/8/8/8/8/PPPPPPPP/RNBQKBNR w - - 0 0"]

1. Nf3 Qaxf3
2. gxf3 Qxf3
3. d4 Qxf2+
4. Kd2 Qee3#

```

It even works with Re8 instead of the Qe8 (though the mate takes a few moves longer).
> 0 votes

---
Tags: chess-variants, point-value
---


# Question
Title: The chess.com engine didn’t show a checkmate
I've attached a screen shot of my game. It is Black’s turn to move. Their king was under check, but not checkmate, as the website didn't show mate.

After awhile, Black had to resign due to not being able to make any valid move. Analyzing the game with a computer results in the move 41. gxh3 being suggested.

How is that possible?

# Answer
As White's previous move was pawn on h2 to h4 then pawn g4xh3 is a legal en passant capture.

For more info - see Rule 3.7.d of the laws of chess
> 17 votes

---
Tags: checkmate, pawns, en-passant
---


# Question
Title: Can anyone explain the motives of this chess engine?
I just played a game against a fairly low-level chess engine, and it made some really weird moves that i cannot see the logic behind. The game goes as follows:

```
[fen ""]
1. a4 d5 2. d4 Qd6 3. c3 Qg6 4. Bf4 Qxb1 5. Qxb1 Kd8 6. e3 Bd7 7. Bb5 Bxb5     8.
axb5 e6 9. Ne2 Be7 10. g3 Nd7 11. O-O g5 12. Be5 f6 13. Bxf6 Ndxf6 14. Qd3
Kc8 15. c4 Bb4 16. cxd5 Nxd5 17. Qc2 Nge7 18. e4 Nb6 19. Rfc1 c5 20. dxc5 Nd7
21. b6 Nxc5 22. bxa7 Re8 23. Qc4 Nc6 24. Nd4 Be1 25. Qxc5 Bd2 26. Rc2 Rxa7
27. Rxa7 Be1 28. Nxc6 Bxf2+ 29. Kxf2 Kc7 30. b4 Rf8+ 31. Ke3 Rf3+ 32. Kxf3
g4+ 33. Kxg4 h5+ 34. Qxh5 Kd7 35. e5 Kc8 36. Na5+ Kb8 37. Rxb7+ Ka8 38. Rc8#

```

The first weird move is 4. Bf4 Qxb1 which exchanges the queen for a knight.

The second illogical move is 26. Rc2 Rxa7, where black sacrifices their rook for a pawn, while already down a queen.

With 28. Nxc6 Bxf2+, black decides not to retake the knight and instead sacrifices a bishop to take a pawn and deliver a meaningless check.

31. Ke3 Rf3+ gives away black's rook, leaving the computer with *no major pieces* against both my rooks and a queen. The computer then proceeds to check me twice with pawns, both of which i take.
32. e5 Kc8 Is the most stupid move, leaving black open to a forced checkmate.

Considering that this computer is set to 'hard' difficulty, i am very dissapointed. Does anyone have any explanation for what might have caused it to make these pathetic moves? I would like to think that it is not designed to let me win, however by the looks of things it is.

# Answer
The engine is only looking ahead one move. Most of these blunders are giving check, but are poorly constructed. It seems that the engine is programmed to think that giving check is always good, but does not check to see if its pieces are defended.
> 3 votes

---
Tags: engines, sacrifice
---


# Question
Title: How do correspondence players keep track of ideas during games?
I've taken up correspondence chess again, and planning has always been one of my biggest weaknesses. It's still something with which I struggle. Besides analyzing specific variations, how do correspondence players keep track of the plans they want to execute, or prevent their opponent from carrying out, during a game?

For example, in a recent game, I knew I needed to not let my opponent put his rook on the 7th rank, as he would likely win another pawn, which I let happen a few moves later.

# Answer
> 5 votes
I write a short description in my notebook for each move I make, unless it is a trivial move (e.g. a forced recapture, an opening move I know already or an endgame that I know already).

I try to imitate the style used in *Logical Chess* by Irving Chernev.

# Answer
> 4 votes
Although it's been many years since I participated, I used to play postal chess by snail mail. For each game I would write down and keep analysis of significant lines each time I moved so I didn't forget them in the interval. I would also write notes concerning what ideas I had in general for the position. I also tried to keep the number of games to a manageable amount to avoid confusion, generally 6 to 12 games at a time. I always had good results with this method.

---
Tags: correspondence-chess, planning
---


title: Is James Damore a FIDE master?

text:
# Question
Title: Is James Damore a FIDE master?
James Damore has been in the news recently because of controversy over this document he wrote while he was an employee of Google's.

The article I had originally read mentioned that he was a chess player, so I searched Google for "James Damore chess" and found this article from "heavy.com" (which I had never heard of). The article stated that he was a FIDE Master, and cited his resume.

\[ edit1: The Daily Wire has echoed this statement that Damore is a FIDE Master \]

\[ edit2: FrontPage Magazine has done the same \]

However, I could not find Damore's FIDE profile, so it seems that he is not even FIDE-rated, let alone a FIDE Master.

It seems to me that there are several possibilities:

1. He *is* a FIDE Master, but somehow the record is missing from the FIDE database. This seems unlikely to me.
2. The resume is not actually his resume (fabricated by someone who is not him). This also seems unlikely since the website on which the resume is hosted looks like it is the official website for MIT's GORElaboratory.
3. He lied on his resume and said that he is a FIDE Master, when in reality he is not. This, unfortunately, seems the most likely possibility, especially since this USCF profile with his name shows a rating of 1817.

---

**My question is: has anybody heard of James Damore in the context of chess? Is he really a FIDE Master?**

# Answer
James Damore is **not** a FIDE Master, simply chech the FIDE Ratings website and search for *James Damore*. As this shows, there are no results.

Notice that there are no possible technicalities for why James Damore is not in the system (things like FIDE lost his paperwork or the possibility that James Damore had a FIDE Master title but then cancelled his FIDE membership or similar) since FIDE keeps track of every single membership even when they are cancelled, so if James Damore ever had a FIDE membership (which you have to have if you are a FIDE Master), he should be in the system.
> 8 votes

# Answer
I believe James Damore **lied** about his resume, and not just about chess.

> https://www.businessinsider.com.au/james-damore-removes-phd-studies-linkedin-2017-8?r=US&IR=T

If he had the courage to lie about PhD in his profile (that's a very **serious** misconduct), why wouldn't he lie about being an FM master?

I can't think of a reason why his FIDE profile is not available, and his USCF rating is just a little over 1800. Hard to imagine we can't find a single FIDE-rated tournament crosstable with his name (he's a young guy and he had to play serious chess games to get an FM title).

James Damore is **not** an FM. He had cheated the media and Google.

**PS:** Note that the media simply downloaded the resume like we did. They had no idea this guy played well below the FM 2300+ rating. Journalists aren't chess players. They didn't have the experience verifying a chess player, but they did quickly send an enquiry to Harvard for his PhD (something they understood).
> 18 votes

# Answer
I checked on the USCF website. There is a James A Damore with a rating of 1817 and no titles. This James is registered in Illinois and last played in the Chicago Open 2005.
> 8 votes

---
Tags: fide
---


# Question
Title: Can you claim an illegal move in Blitz after pressing your clock (but without making a move)?
In Blitz under FIDE rules, Player A makes and completes an illegal move by pressing the clock. Player B states that Player A's move is illegal, does not make a move, but quickly presses his own clock, as if giving Player A the opportunity to correct the move as common in a standard non-Blitz game. Almost immediately, before any other action by either player, Player B realizes that the rules of Blitz apply, stops the clock, and claims the match.

According to Player A, the claim is now "in his time", so is no longer valid. Is this a correct interpretation of the rules?

# Answer
> 3 votes
This is correct. You cannot continue to play (press the clock) and claim a win in blitz. Furthermore in the new rules pressing the clock without making a move counts as an illegal move and so loses (if your opponent claims). This is really just another twist on the old error of taking your opponent's king when he leaves it en prise which again results in you losing for an illegal move instead of your opponent.

In other words, if your opponent makes an illegal move in blitz just claim the game. If you start doing other move-like things (touching a piece, pressing the clock) your claim goes away.

The problem in your case is the same, by the way. An illegal move is only punishable once it is completed by pressing the clock. When you pressed the clock you removed the evidence for the illegal move.

---
Tags: rules, blitz, illegal-move
---


title: Possible chess positon after X ply?

text:
# Question
Title: Possible chess positon after X ply?
I've started to code my own little engine recently and am now working on a perft function which simply sees how many moves there are. Trying to get correct results I searched online for the correct amount of possible positions after e.g. 4 moves. Now according to these sources:

https://youtu.be/6Y\_FaQhqX2c?t=5m46s

It should be 197281 possible positions after 4 moves, and I can reach that in my code!

But switching a bit around in my code to get some optimization which seemingly shouldn't change anything, I get a different number: 197742 Now I would think that is wrong but I have found different sources again, claiming that is in fact correct:

https://youtu.be/Km024eldY1A?t=5m33s

So, which one is it? 197742 or 197281 possible positions after 4 moves? I was a bit uncertain whether this belongs here or on StackOverflow. I went with this one, I hope that's alright.

EDIT: apparently I can't post more than two links due to my low reputation I'll post the links in comments

Thanks in advance Folling

# Answer
> 2 votes
The chess programming wiki is correct:

> https://chessprogramming.wikispaces.com/Perft+Results

197281 is the number. I remember I used Stockfish to generate the same number while debugging my code.

---
Tags: engines, theory, programming
---


title: Requesting draw in last two minutes

text:
# Question
Title: Requesting draw in last two minutes
What is the right way to claim a draw in the last two minutes? Also, is there a procedure to claim a draw after losing on time (I mean if you have a position where you can go for a win if you had time)?

# Answer
> 5 votes
The first point to note that this kind of draw claim only applies when there are no increments. Since digital clocks are almost universal in advanced and normal chess countries it should (I stress "should") rarely arise.

Note also that FIDE proposes to ban analogue clocks and insist on increments in FIDE rated tournaments from 2021, so then the problem should disappear entirely.

There are three cases which can arise:

1) No increments but one or more digital clocks is/are available. In this case the recommended course is for the arbiter to give both sides a 5 second increment, give the claimant's opponent an extra 2 minutes, offer the claimant's opponent a draw which he can decline or accept in the normal way and the game continues to one of the three normal conclusions of win, draw or loss.

2) The player makes a claim that his opponent is not trying to win the game by normal means but just shuffling the pieces quickly to try and win on time. In this case the arbiter will watch the game and if he judges this is correct he will award the draw. He may do this (award the draw) even after the flag has fallen but the claim cannot be made after the flag has fallen and if it is made with just a few seconds left the arbiter will not be able to come to a conclusion and the game will be lost on time.

3) The player makes a claim that his opponent cannot "win by normal means". This is different from "win by any means". For instance if the player is a queen up and crushing his opponent then his opponent might have enough material to win via helpmate but would almost certainly lose if the claimant had enough time.

Another possibility would be if the game was still in the middlegame when, clearly, anything could still happen. In this case the claim would be rejected immediately, the opponent would be given an extra 2 minutes and offered a draw which he could accept or decline.

These are straightforward cases. More problematic would be where the claimant has a rook against a rook and pawn in a theoretically drawn position. This would be the opposite extreme. In this case the arbiter would ask the players to continue and watch the game again possibly until the flag falls. He would then have to judge whether or not the claimant had displayed the required theoretical knowledge to hold the draw. Clearly if the claim is made with just a few seconds on the clock this is not going to be possible and the game is going to be lost.

This same principle applies to all endgame cases where best play would result in a draw but the opponent can win if the player lacks the required theoretical knowledge, even lone king against king and rook's pawn. It should be a trivial draw but the claimant must demonstrate during his time remaining that he has that theoretical knowledge.

Once your flag has fallen no claim can be made even if it is mate in 2.

---
Tags: rules, draw, blitz, claim-draw
---


# Question
Title: What is the native Mac Chess app's rating? Is there a good alternative?
I can't find anywhere what the rating of the Mac's native Chess app is at each level.

Is there a Chess app for Mac that shows the strength bar during the game?

# Answer
> 2 votes
The Mac Chess app engine is the Sjeng engine.

On the old Sjeng website (because Apple Chess is using the old Sjeng) is says:

> For standard chess, Sjeng's rating is probably about 2450 ELO

And I'm assuming that is at its best.

As for looking at each level, there isn't much of a way to know because, beyond the 3 moves ahead area, it starts counting in seconds, and in that realm it depends on the power of the computer. The more powerful the computer, the better it plays because it can look more moves ahead in that time.

TLDR - An estimated 2450 at it's best. It's not a very powerful engine, but it can still whoop most players on it's hardest difficulty.

# Answer
> 0 votes
Hiarcs has a great Mac version with a 3200+ rating.

---
Tags: engines, macos
---


title: Why the analyzer propose this move?

text:
# Question
Title: Why the analyzer propose this move?
My move was Kxc3. The move was labeled as a blunder. Why?

# Answer
Simply put, Kxc3 loses a piece or the exchange after Rc8.

```

[fen "1n3rk1/5pp1/4p2p/8/q1N1QP2/Pnp4P/1PK2PP1/3R1R2 w - - 0 0"]

1. Kxc3 Rc8 2. Rd6 {or any move} Na5 3. Rd4 Qb3+ 4. Kd2 Nxc4+

```
> 4 votes

---
Tags: analysis
---