# Question
Title: Do FIDE rules ban stimulants? Which ones?
Do FIDE rules ban stimulants? I think they ban 'drugs', but would coffee be okay? What about beer or wine?

I hope they ban smoking somehow now.

And I would think that NADH could help old grandmasters play much better. Do not think there is any test for that either.

So what does FIDE ban and what can players take to stay alert and play better ?

# Answer
> 5 votes
FIDE (and probably most of the national federations) would very much like chess to be an Olympic sport because that would lead to massive injections of money into the sport. Hence they subscribe to WADA and have defined drug testing protocols for chess.

The document Chess WADA – Anti-Doping Policy, Nutrition and Health gives details of banned substances relevant for chess:

> The 2018 WADA Prohibited List and Monitoring Program can be found at: http://list.wada-ama.org/
>
> The most relevant banned substances for chess are:
>
> * Amphetamines – e.g. Adderall, Ritalin
> * Ephedrine and Methylephedrine – Prohibited by WADA when its concentration in urine is greater than 10 micrograms per milliliter
> * Pseudoephedrine is prohibited when its concentration in urine is greater than 150 micrograms per milliliter
> * Modafinil
>
> Substances not present on the Prohibited List but represented in the Monitoring Program:
>
> * Caffeine – Included in WADA Monitoring Program and relevant for incompetition testing only. Any urine test reading of less than 12 micrograms per milliliter poses no problem.
> * Codeine – A common ingredient in, for example, preparations used to treat coughs and stomach upsets. Any dosage is highly unlikely to be significant when taken in normal therapeutic quantities.

You say:

> I hope they ban smoking somehow now.

Smoking is obviously banned in the playing area but is permitted in the playing venue if there is a designated smoking area. This is actually spelled out in the **COMPETITION RULES** section of the FIDE Laws of Chess:

> 11.3.4 Smoking, including e-cigarettes, is permitted only in the section of the venue designated by the arbiter

Not every tournament will have a designated smoking area although tournament organizers generally try and also not discriminate against smokers and vapers.

> what can players take to stay alert and play better ?

The first and most obvious requirement for full mental alertness is adequate good quality sleep. FIDE has published its recommendations in Effects of Nutrition and Exercise on Cognitive Performance. There you will find FIDE's common sense guide to good nutrition and hydration.

---
Tags: rules, fide
---


title: Are Elo Ratings Zero-Sum?

text:
# Question
Title: Are Elo Ratings Zero-Sum?
Are Elo ratings a zero-sum system in chess? In other words, if I gain +9 points from a game, does my opponent necessarily take a -9 point loss? If so, would it make sense to say that Elo points are a kind of "currency" which gets traded around the pool of chess players? Would players that are overrated because of playing in a weaker pool have less "purchasing power"?

# Answer
> 23 votes
Between most players, Elo ratings are zero-sum.

The formula for updating an Elo rating looks like this. Suppose player 1 and player 2 are playing a game. First, their ratings are used to generate a prediction: an expected score W that player 1 will get against player 2. Then, we compare this to the actual score, X. player 1 will get K\*(X-W) points, where K is a "development factor" - more on this later on.

From player 2's point of view, the expected score is 1-W and the actual score is 1-X (a score of 1 for player 1 means a score of 0 for player 2, and vice versa). So player 2's rating changes by K\*((1-X)-(1-W)) or K\*(W-X) points, which is the negative of player 1's change. Zero-sum!

The development factor K is the only thing that can break this. In the FIDE version of the Elo rating system, this value is 20 for most players, but it's 40 for new players (to represent the uncertainty in their rating) and 10 for players that have ever had a rating over 2400 (for the opposite effect). If two players from different categories play, then the result will not be zero-sum.

Also, globally, the sum of ratings does change, because players are leaving and entering the pool. A new player starts with an Elo rating determined by their first few games, adding to the supply. That rating may become larger or smaller by the time they stop playing chess for whatever reason - removing another number from the supply.

# Answer
> 13 votes
> Are Elo ratings a zero-sum system in chess?

No, they are not zero sum. There are two reasons for this. First of all, when a player first gets a rating then that is a pure plus. There is no corresponding minus. The player gains a rating of 1000+ (the lower bound of the rating system) by virtue of wins and draws against rated players. Since the player was unrated at the time of the games there is no corresponding effect on the already rated players' ratings.

The second reason is more complicated reason. There is an inbuilt throttling in the rating calculations to limit or exaggerate changes and this is different for different players. This is called the "k factor" or "development coefficient".

Here is the section of the FIDE Rating Regulations effective from 1 July 2017 which describes this:

> 8.55 (a) Use table 8.1(b) to determine the player’s score probability PD
> (b) ΔR = score – PD. For each game, the score is 1, 0.5 or 0.
> (c) **ΣΔR x K = the Rating Change for a given tournament, or Rating period.**
>
> 8.56 **K is the development coefficient**.
> **K = 40** for a player new to the rating list until he has completed events with at least 30 games.
> **K = 20** as long as a player's rating remains under 2400.
> **K = 10** once a player's published rating has reached 2400 and remains at that level subsequently, even if the rating drops below 2400.
> **K = 40** for all players until their 18th birthday, as long as their rating remains under 2300.
> If the number of games (n) for a player on any list for a rating period multiplied by K (as defined above) exceeds 700, then **K shall be the largest whole number such that K x n does not exceed 700**.

This means that, in the extreme case (say a 2290 junior player beating an ageing 2400 rated GM) the winner can gain as much as 4x what the loser loses.

> If so, would it make sense to say that Elo points are a kind of "currency" which gets traded around the pool of chess players?

This can apply when a pool of players never (or almost never) play outside their pool. When the elite players all restrict their play to closed, elite tournaments where only players in the world top 20 then this can happen.

However, in recent years the prize money in large open tournaments like Gibraltar and Isle of Man have reached such attractive levels that more players from the elite have started competing and risking / sharing their Elo points. In particular the 2019 and 2021 Isle of Man tournaments have automatic qualifying places for the Candidates tournament (1 in 2019 and 2 in 2021) which makes it doubly attractive in 2021.

# Answer
> 2 votes
In addition to the other answers: it would depend on the organization running the Elo system as to whether there are additional modifiers.

e.g. back when I was playing chess, the Chess Federation of Canada awarded "participation points" basically points just for playing. Obviously not zero-sum.

The North American Scrabble Player's Association awards both "acceleration points" for performance in a tournament well above expectation, and "feedback points" to the opponents. These are also clearly not zero-sum.

# Answer
> 1 votes
Rating floors make it non-zero sum as other have pointed out. Many years ago, I was talking to a major tournament organizer who supported this. I think one reason (in chess) that they did not want people to be able to lose a lot of rating points was cheating by losing in cheap events and then playing in big-money events against much weaker players. This indeed happened but is really not much of way to earn a living given travel expenses, etc. Nonetheless, "sandbagging" occurred as did player playing under fake names which probably is impossible today due simply to them requiring ID for tax purposes.

But the tournament organizer felt that what caused some people not to play was fear of losing rating points. I thought this absurd -- I think people want ratings to accurately reflect true ability as much as possible but last I checked, ratings have become not only wildly inflated (maybe by 200 or more points over the 1970s) but also in the case of people who have lost skill due to lack of practice etc. simply not reflective of ability and of course this is contagious as they play and other players gain points they would not have if the first player's rating had been allowed to realistically drop.

99.9% or chess players will not make a living at chess but they can try to learn the game and improve (not to mention the social aspect) and I am sure the vast majority of people want a rating that is accurate and meaningful, not fake points that I have seen also obtained by a small club running many rated events but only against each other -- Claude Bloodgood did something like that in prison and became iirc the highest rated player in the USA but he really probably was not even much above master, far below the IM level that would be minimum needed to qualify usually for the US championship that he insisted, based on his fake rating, he be invited to.

---
Tags: rating, fide, elo
---


# Question
Title: Has a highly-rated GM ever lost to a low-rated opponent who didn't go on to become a GM?
Has a highly-rated GM ever lost to a low-rated opponent who didn't go on to become a GM?

Also, currently has there ever been a GM who lost to low-rated opponents on a consistent basis?

# Answer
> 5 votes
There was one famous reported game supposedly won against Mexican GM Carlos Torres by an amateur, E.Z. Adams, who did not go on to gain additional fame in the chess world

http://chicagochess.blogspot.com/2009/11/ez-adams-carlos-torre-new-orleans-1920.html

But this game is "suspect" because Adams was Torres' financial backer. So there is a suspicion that the game was "thrown" by Torres, or even made up.

# Answer
> 7 votes
There is a book called "Great Chess Upsets" by Reshevsky, but unfortunately most of the games are not upsets at all, but one famous player against another. Reshevsky himself, in his first major tournament, beat Janowski even though he was prepubescent. Prior to the tournament Janowski bitterly complained to the organizers that they were spoiling the gravity of the event by allowing children to play in it. After he won, Reshevsky reporting starting jumping up and down shouting, "I beat a grandmaster! I beat a grandmaster!".

Some of the more notable upsets:

In 1905 Frank Marshall, a World Championship candidate, lost to the unknown Dutch player Dirk Bleijkmanns at the Scheveningen Masters Tournament.

Joel Fridlizius beating both Alekhine and Spielmann at the Nordic Masters Tournament in 1912.

At the great St. Petersburg Tournament of 1914, the winner, Alexander Alekhine lost to German lesser light Bernhard Gregory.

In the 1923 Scheveningen Match Tournament, Spielmann lost to the little known Dutch master George Fontein.

In the 1924 Masters Tournament in Merano, Rubinstein lost to unknown player Gyula Patay.

Max Euwe lost to Vera Menchik at the 1930 Hastings Tournament, thereby becoming a member of the "Menchik Club".

The Cuban master Guillermo Estevez Morales beat Mikhail Tal after Tal blundered the exchange.

Croatian master Josip Rukavina beat Korchnoi at the 1973 Interzonal.

The unknown Ecuadorian player César Muñoz beat Bobby Fischer at the 1960 Leipzig Olympiad.

Bernardo Wexler beat Fischer at the 1960 Buenos Aires tournament.

An unknown player named Robert Burger beat Bobby Fischer in 12 moves in a simul after Fischer fell into a surprising trap of the queen.

Israeli Alexander Huzman beat Kasparov in the 2003 European Clubs Cup in 24 moves after Kasparov blundered two pawns because he missed a mate threat.

# Answer
> 2 votes
A trivial example would be in simuls, where you can find any of a million examples.

Another case where there's quite a few would be in blitz/bullet games. In fact, someone I know once beat Gawain Jones (an extremely strong player, currently #74 in the world) twice in bullet (game 1 and game 2). Admittedly, she's not exactly low rated, but there's surely cases as you described.

Odds are there's hundreds or tens of thousands of cases that fall under these two categories.

The chess.com article The Greatest Chess Upsets, Part 1 also lists a number of these upsets, although they are fairly highly rated players.

The Quora question Has a chess grandmaster ever lost to an amateur? gives a number of examples, although it's worth noting most of these had special circumstances, such as time odds or simul.

James Mortimer beat a number of great players of his time, despite being not very good. However, it's unclear if he'd count since there were no real ratings at the time.

TLDR: Yes, but most are under special circumstances such as time odds or simultaneous exhibitions.

# Answer
> 2 votes
One thing about GMs is consistency so losing in a tournament game to a significantly lower-rated player is extremely rare and the rarity can be roughly calculated based on rating difference. So a 2500 losing to 1500 might be 1/100 or less. Also, the way tournament pairings are done makes it pretty unlikely, even in an open event and impossible in a class event, for a GM to even play a 1500.

So it may literally be true that zero GMs (in modern times with modern ELO ratings) have ever lost to a 1500 in a normal tournament. There are firstly not that many GMs, secondly the 1500 would have to play in something like the US Open and win his first game against probably a low master and then of course beat the GM and THEN not become a GM. So maybe never happened.

On the other hand, Perry Youngworth was a promising junior (14 or 15) who did beat a GM in 1978 US Open. He was either a low master or a high expert at the time so not a huge upset especially since he was an up-and-coming junior whose ratings often rise very fast at that age but still a surprise. Nonetheless, he never became a GM or even an IM, I think. So depending upon whether you want to call an expert beating a GM an upset, there is that example but if experts beating GMs do count, I am sure there are a lot more.

Becoming a GM is not easy and used to be a lot harder -- there are many well-known and respected players (for their playing ability) who, due often to inability to get to tournaments of the necessary level of competition, never reached GM but "only" reached IM level. There are players who won the US championship without ever becoming GM (John Grefe and Stuart Rachels are listed as the only two).

---
Tags: history, famous-players
---


title: Why is a6 strong in this position?

text:
# Question
Title: Why is a6 strong in this position?
I was spectating an online simul given by a GM (this game in particular) and as the game was played I was very surprised to see GM Chessweeb play 24... a6.

Here is the position.

```
[Title "Black to move"]
[StartFlipped "1"]
[fen "7Q/ppk1qp2/4p3/3pPp1P/5P2/2P5/PP4r1/1K1R4 b - - 0 24"]

```

I was expecting a continuation like 24... Qh4 25. h6 Qxf4

Stockfish confirms that a6 is indeed the best move but I'm having trouble understanding why that is. The only thing I can think of is perhaps a6 gives the king a hideout to prevent future perpetual check?

# Answer
> 3 votes
You're correct. The idea of 24...a6 is to allow the king to avoid a perpetual. This could be of relevance if Black's queen moves away to go after White's king (e.g., ...Qc5). It could also be useful for the king to hide on a7 if things go haywire and a dangerous attack happens, such as the h-pawn promoting or White's rook getting involved. Although, in the position before 24...a6, Stockfish gives an evaluation of 0.00 no matter whose move it is. So purely in an objective sense, ...a6 isn't a necessary move -- but practically it's quite nice. Your anticipated move of 24...Qh4 is also evaluated at 0.00 by Stockfish, so it's just as good.

One interesting line goes 24...a6 25.h6 (White has other moves that are fine too) 25...Qc5. Now White's going to get mated from ...Qf2 if he's not careful. For example, 26.Qe8 Qf2 27.Qe7+ Kb8 28.Qf8+ Ka7. Now White can't stop the dual threats of ...Qxb2# and ...Qc2+ (picking up the d1-rook with mate). Another faulty try is 26.Qg7. The idea is that 26...Rxg7 27.hxg7 sees White about to promote, leaving him up a rook. However, Black has 26...Qf2, and 27.Qxf7+ Kb6 28.Qxe6+ Ka7 sees Black's king being safe, again thanks to the a6-pawn. Therefore, White's only 26th move which maintains equality is 26.Ka1!, preparing to defend with Rb1 if needed.

---
Tags: learning, beginner
---


title: From Mate-in-3 to Mate-in-1

text:
# Question
Title: From Mate-in-3 to Mate-in-1
Here is my new problem in 3 steps - the key designates here the piece that moves first in the solution. An other way to reach a mate in one I hope you'll enjoy...

```
    [Title "From Mate in 3 to Mate in 1"]
    [FEN "5R2/p2k1p1P/1P1P1PPr/bPpKBN1p/1pR3n1/7B/2P2N1P/1b6 w KQkq - 0 1"]

```

Here is the starting position. White to move (at each step)
Step 1 : Mate in 3
Step 2 : Remove the key then Mate in 2 (same starting position with one piece less)
Step 3 : Remove the key then Mate in 1 (same starting position with two pieces less)

**Edit.** For Step 3, say White R8 hasn't capture any piece at last move.

# Answer
Spotting potential mates isn't too difficult. There are a couple of obvious ones involving the b and h pawns which aren't far off from promoting. An immediate b7 threatens b8=N# for example. It can only be stopped by Bc7 but then after dxc7 black has Nxf6+ and the mate is delayed beyond 3 moves.

Pushing the h pawn is more promising. If it weren't for the black rook on h6 then it would be mate in 2 with Rxf7+ followed by h8=Q#. That can be fixed by starting with Nxh6.

Going back to the initial position it's worth looking at possible black spoiler moves, moves which either deliver check or threaten check which delay the mate. We've already seen that Nxf6+. Also Ne3+ and Ba2 threatening Bxc4+ if black is given the opportunity. If the mate is going to involve the Bishop on h3 delivering the coup de grace then we also have to watch out for Rxg6 followed by Rg4 blocking the check.

That said the key move of Nxh6 solves a lot of these problems. It gets rid of the pesky rook and it pins the pesky knight on g4. Hence I think the first part goes like this:

```
[Title "First part - mate in 3"]
[fen "5R2/p2k1p1P/1P1P1PPr/bPpKBN1p/1pR3n1/7B/2P2N1P/1b6 w KQkq - 0 1"]

1. Nxh6 Ba2 {threatening to disrupt with Bxc4+} 2. Rxf7+ {thank goodness this comes with tempo and black has no time for the disruptive check} Ke8 3. h8=Q#

```

So, remove the f5 knight and try and mate in 2. The b7 push is obviously too slow so the obvious line to take is mating with the h3 bishop.

The obvious first try is Nxg4. The problem is that black is not obliged to take with hxg4 allowing Bxg4#. Instead black has the tricky Rxg6 followed by Rg4 to block the mate. Mate in 2 is denied.

So, how to stop this defence? The cunning answer is to take with the rook. Then Rxg6 can be answered by Rxg6# or, to rub it in, Rg5#. What about Ba2+? That was one of black's disruptor moves. Does that stop us? No! We can just move the rook back to c4, blocking the check and delivering a discovered mate.

So:

```
[Title "Second part - mate in 2"]
[fen "5R2/p2k1p1P/1P1P1PPr/bPpKB2p/1pR3n1/7B/2P2N1P/1b6 w KQkq - 0 1"]

1. Rxg4 (1. Nxg4? Rxg6 2. Ne3+ Rg4) hxg4 2. Bxg4# (1...Rxg6 2. Rxg6#) (1...Ba2+ 2. Rc4#)

```

That then leaves this as the final problem. As @wimi points out the key here is to spot the possibility that black's last move could have been c7-c5 meaning that bxc6 en passant would be checkmate. Great spot by @wimi.

```
[title "Third part - mate in 1"]
[fen "5R2/p2k1p1P/1P1P1PPr/bPpKB2p/1p4n1/7B/2P2N1P/1b6 w KQkq - 0 1"]

1. bxc6#

```
> 9 votes

---
Tags: checkmate, problems, puzzles, retrograde-analysis
---


# Question
Title: Who is Yuri Dojoian, Kasparov's analyst in the 90s?
Long time ago I read about this strong GM who was one of Kasparov's analysts in the 90s. The thing is that if I search by "Yuri Dojoian" I only get a few results, only in Spanish media, like this one. I'm almost sure there is another way to write his name, but I have no idea how could it be.

# Answer
> 11 votes
I think the player you are referring to is Yury Dokhoian. According to his FIDE profile and Olimpbase profile he has not played competitive chess since 1994. According to his Wikipedia page he was Kasparov's second for many years and later started working with Karjakin. Chessgames.com has 173 of his games.

---
Tags: history, kasparov
---


title: Why does Black play Bh3+?

text:
# Question
Title: Why does Black play Bh3+?
This puzzle on chesstempo caught my eye (we play as White):

```
[FEN "2b2rk/1p3ppp/r/p1p/3pP1Pq/1P1P/P3BPK/1RB1QR2 b - - 0 1"]

1. Bg4

```

I reckon Black needs to try skewering the rook with the bishop that captured the pawn.

I made a wrong move. It doesn't much matter to the question, yet I wanted to show this nice way Black may mate after my mistake:

```
[FEN "2b2rk/1p3ppp/r/p1p/3pP1Pq/1P1P/P3BPK/1RB1QR2 b - - 0 1"]

1. Bg4 Bg4
2. Qg4 Kh2
3. Qh4 Kg2
4. Rg6 Kf3
5. Qg4

```

Anyway, the right move was this:

```
[FEN "2b2rk/1p3ppp/r/p1p/3pP1Pq/1P1P/P3BPK/1RB1QR2 b - - 0 1"]

1. Bg4 Rh1

```

I see no point to Bh3+ now, yet Black plays just that and gets the bishop captured:

```
[FEN "2b2rk/1p3ppp/r/p1p/3pP1Pq/1P1P/P3BPK/1RB1QR2 b - - 0 1"]

1. Bg4 Rh1
2. Bh3+ Rh3

```

The king protects the rook, therefore it shan't be captured by the queen.

Why does Black play Bh3+?

# Answer
> 13 votes
Black is going to lose the bishop regardless. White is attacking the queen in such a way that it will have to move (or be captured), and there are no available safe squares from which it can continue to protect black's bishop. After the queen retreats, white will be free to capture the bishop with his bishop. By playing Bh3 first, black can at least generate some small counterplay by opening up the file so his rook can come check the white king, while white's bishop remains on a somewhat passive square.

# Answer
> 10 votes
You haven't understood the puzzle. The puzzle asks you to find the best move for white after Bxg4 by black. It does not ask you to find the best move for black after Rh1 by white.

Having found Rh1 for white the moves that follow are illustrative only. They do not show all the possible black replies and there is no suggestion that the line chosen for black is a lot better for black than the alternatives.

In the computer's evaluation the position after 2...Bh3+ 3. Rxh3 Rg6+ will count as marginally better because the rook is more actively placed. The difference is irrelevant because both positions are equally lost.

---
Tags: puzzles, defense
---


# Question
Title: What is the Universal Rating System (URS)?
While watching this year's 2020 Champions Showdown Chess 9LX I noticed they gave players' ratings according to the URS or Universal Rating System. Which are the characteristics of this rating system?

# Answer
> 4 votes
The Universal Rating System is an alternate rating system which, according to the project's web site:

> The Universal Rating System™ (URS™ for short), is a revolutionary new sport’s rating system designed to assess the relative strength of participants across a wide variety of competitor vs competitor sports or games.
>
> The URS™ was developed as the result of a collaborative research project funded by the Grand Chess Tour, the Kasparov Chess Foundation and the Chess Club and Scholastic Center of Saint Louis.

According to the project's FAQ page, the major differences between URS ratings and FIDE Elo ratings are:

> There are many differences between the URS™ and the FIDE system. The most striking difference is that the URS™ calculates only one rating for each player, informed by their results at all rates of play. This published rating is the URS™ system's assessment of each player's strength at Classical chess (defined as a rate of play where each player has at least 2 hours for their first 60 moves). The URS™ recognizes that there is useful information about a player's over-the-board chess strength in all game results regardless of the time limit, and can therefore more effectively estimate a player's Classical chess strength by also considering their results at games played at faster time controls. As the speed of play increases, the URS™ assigns less and less importance to the game results relative to games played at slower time controls.
>
> Furthermore, the URS™ is a weighted performance rating, calculated across several years of previous game results for all players. Older games are given less importance than more recent games, by applying an exponential decay rate. Unlike traditional performance ratings, which are based upon the opponents' rating at the time the game was played, the URS™ constantly reassesses the strength of all opponents and searches for the most likely set of current ratings for all players, in order to best explain the observed results.

---
Tags: rating
---


title: Is the chess problem a dead form?

text:
# Question
Title: Is the chess problem a dead form?
Or, to ask the question a bit less opinionatedly, "what new ideas have been introduced in chess problems over the last 20 years?" I imagine many problems have been composed in that time, but it seems like all of the stipulations (model mates, selfmates, etc.), all of the structural elements (pinnings and unpinnings, interference, and so on) and all of the tasks (Phoenix tasks, etc) have been long since sussed out. The only relatively recent development that I'm aware of are various 'Babson cycles' that have been composed by Peter Hoffmann (see Wikipedia's page on the Babson task for details). Are there any other relatively recent developments of note in chess problems?

# Answer
An unsorted list of arguments for the vitality of chess problems (probably my answer is a little bit biased because I am an enthusiastic chess composer ...)

* **Computers**: A lot of new ideas have been developed during the last decades. One reason for it is the rise of computer programs which help to check the correctness of a chess problem. This simplified the chess composition dramatically, especially selfmates and helpmates with very complex and long solutions are now possible...
* **Helpmates**: by the way help mates. This is an area I know a little bit and during the last 20 years there was phantastic progress. Here some non representative samples http://kobulchess.com/en/problems/originals2013/321-chess-problem-helpmate-viktoras-paliulionis.html or http://www.yacpdb.org/#320933 or http://pdb.dieschwalbe.de/search.jsp. Study the solutions and look for other problems of these authors (and other like Caillaud, Mazlar ...) to find other good help mates ... also there are still many open themes which are not realised. such as the '100$ theme' , the 'Oudot theme' or a helpmate with more than 27 moves...
* **Specialisation**: Chess compositions branch in many different ways. Some "theoretical" knowledge on certain themes is restricted only to a very small group of composers. So for example if you ask for the development of some themes for three movers (mate in three) the current state of the art is probably known only to a very small group of composers (probably less than 100 people world wide). I am definitely sure they know exactly how their field developed during the last years. And definitely they will argue for a good progress in their field of work. But from "outside" the progress seems very modest (of course I don't want to blame the three mover community but this is an area I know almost nothing :-)... There is a similar situation in mathematics or other scientific areas where the current state of development is often only understood by a small group of experts...
* **Fairy chess**: If you think of chess problems in the broader sense of generalized chess the we come to fairy chess. This is the genre where the chess rules and the stipulations are extended far beyond the orthodox setup. For example new varieties of chess (varieties of circe chess, ghost chess ,... et.al.) and many many different pieces have been developed during the last decades and all of them help to represent new ideas in chess problems (or can you think of triple check or ...). For much more on fairy chess look at juliasfairies.com
* **selfmate, retro problems ...**: There are a lot of other areas where chess problems develop. For example look at the (german) retro blog http://www.thbrand.de/retroblog/ where you can learn a lot about retro chess (if you are aware of german)...

I hope all this helps to believe in the vital functions. For much more infos check the websites I mentioned above
> 20 votes

# Answer
Oliver Sick listed many good examples. Here are some of my thoughts:

* Andrew Buchanan's "Dead Reckoning" (a consequence of Article 5.2b of the Laws of Chess)
* Helpselfmates
* Parry series mates
* Goals other than (stale)mate, e.g. check, capture, or White to move a unit to a specified square.

Further developments in genres that are more than 20 years old, e.g.:

* proof games
* retractors

The idea of the task is more than a century old, but recently new sorts of task have been invented and worked on, e.g. construct the longest sound problem of a specific genre and with a specified number of units (or with specified force) in the diagram.

There's more information about various chess problem genres at
> 11 votes

# Answer
I can only speak of the direct twomover genre, where I am...less nonexpert. The twomover has been declared dead more often than all members of the X-Men combined, and yet it is still alive. True, the classics all have been found. Probably. But there always have been new ideas. (Suggestion: look up who got a grandmaster title in the field, check his problems in the original sources and what the audience commented.)

And Fairy Chess is unlimited by definition (and practically depends only which novelties catch on with composers and public).
> 4 votes

# Answer
I'm not aware of any recent examples beyond the "cyclic Babson" type of problem mentioned in the Wikipedia article you posted. I would agree that virtually all meaningful tactical motifs (pins, deflection, desperado, different types of mates, etc.) have been classified, as well.

In my opinion, problems like the Phoenix example are remarkable because they defy our natural impulse to evaluate a position against an instinctive set of strategic patterns and rules, and instead bluntly illustrate the fact that chess is fundamentally a tactical game.

The Babson Task class of problems seem to have particular aesthetic value because they exhibit "other interesting properties" (I'll call them OIP) - in this case, the symmetrical beauty of White's promotion to any of the four possible pieces that Black promotes to (or some asymmetric mapping in the cyclic case) - as part of the forced sequence.

I would argue that the OIP within such chess problems augment the aesthetic value of the composition; if a problem has no or some incomplete set of OIP in its solution, then its aesthetic value is less than a problem which contains a more complete or harmonious set of OIP. Thus, the example of the Wolfgang Pauly composition mentioned in the Babson Task Wikipedia article could be said to have less aesthetic value than a true Babson problem because of the fact that the Bishop under-promotion does not force a win.

As an example of why the chess problem might not be a 'dead' form of art, I might conjure up a hypothetical class of problem with an intriguing set of OIP, or extend the depth of an existing scheme, for which an example might at least conceivably exist. I'm no good at this, but as a poor example, let's take a variation of the Allumwandlung pattern: perhaps a set of initial conditions exist such that White can forcibly win by promoting an a-pawn to a Rook, or a b-pawn to a Knight, or a c-pawn to a Bishop, or a d-pawn to a Queen. The OIP of such a solution would have obvious relevance for the fact that these files correspond to the starting position of Black's pieces. Voila - define a set of OIP, in this case a more restricted type of Allumwandlung (the easy part), and if one qualifying initial condition can be found to satisfy these boundary conditions (the hard part), a new class of problems is born.

On the other hand, perhaps we have already classified all plausible and meaningful OIP.

While I find it difficult to believe that the chess problem as an art form is dead, I do think that there are limits to to the number of classes of chess problem that would be of interest to human beings, due to our relatively limited ability to evaluate concrete lines beyond a certain depth.
> 3 votes

# Answer
As these posts show -"A mysterious mate in one", "Another Unusual Mate in One", "Mate in One the Missing King\- Mate-in-Ones can be renewed. If it can be so in this very narrow field of problems, it can be everywhere. The only limit is our imagination.
> 2 votes

---
Tags: problems, history
---


# Question
Title: Why is it a mistake to capture the forked rook?
In a recent game, I forked a queen and rook with a knight. After seeing no immediate threats from 8. Qf4 I immediately captured with 8. ...Nxb3. Apparently this was quite a mistake (a 213 centipawn evaluation drop), but it's not clear to me why the material advantage from Nxb3 is inferior to Stockfish's recommendation of Nxc2, let alone *far* superior.

```
[White "White"]
[Black "Black"]

[fen ""]

1. e4 c5 2. Bc4 { B20 Sicilian Defense: Bowdler Attack } b6 3. a4 Bb7 4. Qf3 e6 5. Ra3? { (-0.77 → -2.15) Mistake. d3 was best. } a6 6. Rb3 Nc6 7. Nh3? { (-2.78 → -5.30) Mistake. Re3 was best. } Nd4 8. Qf4 Nxb3? { (-5.02 → -2.89) Mistake. Nxc2 was best. } 9. Ng5?? { (-2.89 → -6.87) Blunder. Bxb3 was best. } f6 10. Nxe6 dxe6 11. Bxe6?! { (-5.59 → -10.58) Inaccuracy. Bxb3 was best. } Nd4 12. Bg4 Nxc2+ 0-1

```

What am I missing here? Why shouldn't Nxb3 be played (or maybe, why is Nxc2 far superior)?

# Answer
> 8 votes
The key point is that taking the rook reduces your positional advantage.

* Your knight is active but the rook is passive;
* With your knight on `d4` the squares the rook can move to are extremely limited. After `8. ... Nxc2+ 9. Kf1 h6`, only `f3` and `g3` are better squares for the rook. However, with the advancement of pawns on the king side, the queen will be chased away and the development of `Nf6` will trap the rook. This will gain both the material advantage and the increasing positional advantage.

This is reflected in the Stockfish evaluation as `Nxb3` yields -2.3, with the -2 coming from the material whereas `Nxc2+` yields -3.8.

# Answer
> 4 votes
Note, also, that Nxc2 is +1 on material while Nxb3 is +2 as the knight should be captured--I do not see why your opponent launched that futile attack and let the knight escape.

However, along with that +1 material the king has to move, costing him several moves to get the rook out and the king to safety.

# Answer
> 1 votes
A 213 "centipawn" loss can be critical in an equal position. If you still have a +9 position, it's irrelevant. In this case, I think the engine dislikes to take the rook right now because 8...b5 looks like a stronger move. If White removes the bishop, you can still take the rook, while 9.axb5 axb5 would make your ...Ra1 threat unstoppable

---
Tags: analysis, strategy, tactics, evaluation
---


title: A riddle just for curiosity

text:
# Question
Title: A riddle just for curiosity
The position is a variation of a computer game.

```
[FEN "8/3k1R2/2p1p3/2PpP3/3P1P2/6r1/4K3/8 b - - 0 1"]

```

Can this position be won by white ABSENT the fifty move rule? I know this is mostly exotic, because a eleven , or nine pieces position will be considered a draw under current rules both in over the board chess and in correspondence chess. Nevertheless , I am curious to know. Can the fortress be broken , even if it takes more than 50 moves?

# Answer
The position very much looks to be a draw. The white king can't advance easily as the black rook stays on the third rank. All the maneuvers to bring back the white rook to help advance don't seem to work as both f4 and d4 can be weak. Furthermore the black king can stay on the d file to cover the e7 and c7 square while always having Kd7 if White attacks the weak e6 or c6 pawn from the side.

Therefore the only way to make progress for White is to play 0...Kd8 1.f5 exf5 2.Rxf5 Now White faces a similar problem. The d4 pawn is weak so as soon as White blocks with the rook on the third rank the black rook will move to the fourth rank and keep the d4 pawn attacked. For instance 2...Rh3 3.Rf3 Rh4 . To make progress White would have to block the fourth rank. However if White plays Ke3 Black can respond with Re4+ forcing the king to d3 from which it can not support a move like Rf4 blocking the fourth rank.

This of course is not a proof but I am very sure that for the reasons outlined here, the position is a draw under all circumstances.
> 2 votes

---
Tags: rook-endgame
---


# Question
Title: Establish Rating System for My Community
I want to establish a rating system for my community.

1. I've decided to publish the rating every 1st January, April, July and October.
2. Every new player will be given a rating of 1200.
3. Using result submitted to me by tournament organisers, I will get every players' Rating Performance for any tournament.
4. Every time I want to publish a new rating, I will calculate the Average Rating Performance for every player.
5. Let say between January to April, Player A's Rating Performances are 1300, 1200, 1400 (Player A participated in 3 tournaments)
6. So by April 1st, Player A's rating is (1300 + 1200 + 1400)/3 = 1300

Is this correct?

# Edit

To put it simple, am I correct to use Player's Rating Performance to base my rating system?

Or should I calculate players' rating based on every player's encounter using calculator like this: https://ratings.fide.com/calculator\_rtd.phtml ?

# Answer
It is better to look at every game. Only looking at tournament performances causes you to lose some important information.

Should a 4 round tournament count the same as a 9 round tournament? Under your system, they count the same. That doesn't seem right.

I had a tournament recently where I won against 3 low-rated players and drew against a player rated over 2000. My performance rating was 2041. But there's a difference between a 2041 performance done this way, and a 2041 performance achieved by scoring 2/4 against players rated over 2000.

It's worse when a player wins (or loses) every game in a tournament. Are you going to make a player's rating go *down* after they win every game, if their opponents were too weak and thus the performance rating for that tournament was low? That doesn't seem fair.

Also, what happens during the next rating period? How do you account for the fact that the player already has a rating? Are you averaging in the old rating? But if a player with a well established rating plays in one tournament in a period, simply averaging the old rating and the one new tournament seems to put too much weight on the one new tournament.
> 9 votes

# Answer
The way elo works is that they take current rating and tournament performance, and then adjust a new rating based depending on k-factor. For all intents and purposes they count every game during a tournament as happening at the same time. So your step 6 is wrong because it doesn't weigh the latest result more than the previous tournaments. If somebody plays their first 10 tournaments with a performance of 1200 and then their last 5 tournaments they played at a 2000 level, they are clearly much closer to 2000 strength than 1200 now.
> 0 votes

# Answer
Starting new players at 1200 will distort the ratings and make it take longer , with a LOT more games played in total, for the ratings to settle down to anything near accurate.

You should first have a big tournament where most all local players play a lot of rounds. Swiss would work best if you have more players than you could have enough rounds for a RR.

Then set initial ratings based on results not some PC approach where everybody starts with 1200. Some players will be experienced and have very high actual ratings while some will be beginners whose actual strength is very low. Starting them off equally is nonsense.

Statistically far better to rate each player based on each specific game rather than some so called average performance that might not reflect reality as well as each game individually does.
> 0 votes

---
Tags: rating, elo
---


title: NNUE Based Engines - Post Move Analysis

text:
# Question
Title: NNUE Based Engines - Post Move Analysis
Its a bit of a wordy question as there is a lot of background to provide context for thinking and analysis so for that I apologise you can skip the background if you want but it might provide some additional context that might be useful.

**The Background:** Came across an interesting position today which has resulted in me going down a rabbit hole of analysis.

Generally Whites position is looking reasonably strong and is up in material. The d6 pawn is safe from capture because mate would quickly ensue with Rxc8. The black c8 bishop is out of play as long as Black doesn't move his king. The biggest issue is for White at the moment is the knight on g5. It is preventing Blacks king escaping through f7 but otherwise is fairly useless in this position.

The position arises on move 30 with Black playing h6. The knight having no escape squares is going to fall. To make matters worse the knight has no capture possibilities or defence possibilities.

Ultimately I played Ne6 , the pawn took leading to promotion and ultimately Blacks resignation. I decided to do some analysis on this position and found that the engines really didn't like this position and repeatedly provided the wrong moves unless until they were shown the move. I could clearly see Ne6 in the lines but for some reason it would suggest Raa8 over Ne6 but the second Ne6 was played it would read that as the better and stronger move.

**Question:** Why do some engines fail to locate best move options even though it analyses the position and only updates it as the correct move after it has been played? Is this common in NNUE based engines?

*Example*: Komodo Dragon, Stockfish 12 and Lc0 all saw 2. Raa8 (Scenario B) as a better move than Ne6 (Scenario A) until it moved passed that move and then saw Ne6 as the stronger move

**Scenario A**

```
[Date "Nov 2020"]
[White "Yours Truly"]
[Black "Random Hero"]
[Result "1-0"]
[Event "Scenario A"]
[FEN "1Rb3k1/3p2pp/2rP4/4p1N1/4P3/5P1P/6P1/R5K1 w - - 0 30"]

1. h3 h6 2. Ne6! dxe6 3. d7 Kf7 4. dxc8Q Rxc8 5. Rxc8 1-0

```

**Scenario B**

```
[Date "Nov 2020"]
[White "Yours Truly"]
[Black "Random Hero"]
[Event "Scenario B"]
[FEN "1Rb3k1/3p2pp/2rP4/4p1N1/4P3/5P1P/6P1/R5K1 w - - 0 30"]

1. h3 h6 2. Raa8 hxg5 3. Rxc8+ Rxc8 4. Rxc8+ Kf7

```

# Answer
> 4 votes
This is just an issue every engine has (although they may miss different moves). In this case, it just pruned (ie, didn't consider/didnt consider enough) Ne6. It's not *common* per se, but has to be kept in mind

Also note Lc0 is not NNUE, it is just a normal neural network not NNUE which is special.

# Answer
> 1 votes
I think NNUE engines are right because after Ne6 black can play Rxd6 instead of taking knight(that exchanges all of his major pieces). he loses bishop after Rxd6 but his rook will remain and he has some chance to go on even if that is 1%. but after Raa8 hxg5(the only move because khight on g5 supports king's scape way and there is checkmate threat) Rxc8 Rxc8 white will have a rook but black won't have any major piece and all of his remaining pieces will be pawns and king so his winning chance is less than the previous line I think

---
Tags: engines, analysis
---


# Question
Title: How to keep improving when missing advanced knowledge prevents finding the answer to tactical puzzles
I consider myself to be an intermediate player. I understand the tactical motifs well and can solve quite a few tactical puzzles with relative ease. I have also dedicated time at working on end games and can handle the basic ones with major and minor pieces as well as the ones involving pawns decently.

Lately I have been paying a lot of attention at the tactical problems that I get wrong and I have noticed that for the most part, the reason of my mistakes is that I don't know how to correctly evaluate the resulting position correctly to pick the right move.

For example: I don't really have a diagram but the question is more general than specific so, please bear with me. In a recent one I found the correct first move and on the second one I chose to exchange a knight for a rook thinking I would end up with an advantage in quality. That turned out to be a mistake. The right answer was to take a bishop which made the queen to take my knight which was defended. I kept thinking "why on earth would the queen take the knight if it is going to be taken? It makes no sense".

I know that the right answer boils down to the specific position, even when analyzing it with the engine I could see that in this case, by taking the rook the advantage was completely lost and if the other side did not take with the queen, the advantage I had would rise exponentially.

My questions would be, how can I learn this stuff? What kind of sources do I have to look for? What subject should I Google? What kind of books, or better yet, titles can I read so that I can start understanding this?

# Answer
> 10 votes
I think the most important thing to do right now is to clarify exactly what the problem you're having is. From the somewhat vague example you gave I have a suspicion, but I can't be sure. I think that your problem with the tactics is that the way you evaluate the resulting positions from the tactical sequences you calculate is too simplistic, in this case by being over-reliant on the material count while not taking other positional factors into account.

From the way your example is phrased, it seems to me like you can understand that the resulting position from the correct solution is better than the one resulting from your solution **when you compare the end positions next to one another**. So it might be a case of you knowing that you're solving a tactical problem, and therefore you assume that you're looking for a way to win material, causing you to "tunnel-vision" when solving these tactics exercises. In this case, the solution to your problem is rather simple in nature: just be aware that finding the best continuation to a problem is not always the same as finding a way to win material, it's all about ending up in the best possible position.

Another potential problem that could be the issue for you is that you stop your calculation too soon; sometimes it's necessary to calculate further than you originally expect to see why a continuation is good or bad, and if this is the case for you (which it could be, judging by your example) then you need to ask yourself why you stopped calculating at the point that you did. Why didn't you notice that you needed to calculate a few moves further? And if you were to calculate further, would you have been able to see what was wrong with your line? In this case, it is vital to be aware of this if you're ever going to fix the issue in the first place, and to appreciate the importance of calculating to the very end of the line, where the position has clarified to the point where it's easy to evaluate directly.

In the end, I seriously doubt that all your problems with these more "advanced" tactics are based in a lack of "advanced knowledge" of positional chess. I think it has more to do with your approach/attitude to calculation might be somewhat misguided and/or overly simplistic. But in the end, this is hard to judge from one vague example, and I might be way off in my assessment of your particular case. In any case I felt that what I've stated here needed to be stated so that you are at least aware of some of the potential pitfalls with tactics that are easy to overlook if you're not aware of them.

# Answer
> 5 votes
In your example the opponent was forced to exchange his queen for a knight.

That usually means that

1. They will win material on top of that to minimize material loss (2 pieces and 2 pawns for a queen is materially better than just being a piece down). Converting material advantages is mostly a matter of endgame technique and then trading down into endgames. There is a new book by Gelfand "Technical Decision Making in Chess" which is dedicated to converting static advantages. Of course there are also decent free resources on the topic of converting material advantages.
2. The knight was a key attacking piece and the attack was not holdable. Seeing an attack and correctly judging it is not only a matter of tactics, but also understanding how to conduct an attack. On that topic I really liked "Attacking Manual" by Jacob Aagaard.

# Answer
> 4 votes
To be honest you are not as advanced as you think you are.

If you are talking about tactics then almost always there is a clear material advantage or mate resulting from doing the tactics. How is it you are advanced and cannot see such an advantage?

In some cases the advantage may be positional. Clearly your experience and positional understanding is lacking. I know of no really good materials to teach you positional understanding although there may now be some on the internet. It may just take a lot of playing to gather experience to appreciate the positional advantages as well as material ones. When you finally understand that position is far more important than material you will be ready to grok those problems that you are getting wrong now.

OTOH those tactical problems on line do not always have the best solution just what somebody claimed was best.

For us to help you better then please provide specific positions and ask about those. Also tell us what your FIDE rating is that makes you think you are at the advanced level you keep claiming you are.

Having played almost 70 years your comments sound like a kid of about 12 with helicopter parents telling them how great they are. You might be a 40 year old with a phd but you do not come across as an adult at all. Especially when you keep asserting that there is some advanced knowledge out there if only we would tell where it was hidden then you could be a world class player.

---
Tags: learning
---


# Question
Title: Study endgame first before studying opening? Is it true?
While looking for and comparing suggestions that will help me to improve in chess, I have noticed that some people and some chess book authors suggest that you should study the endgame first.

Some people say that by studying endgame first, you will find out the correct middlegame plan to achieve the endgame that will be on your favor.

Is it effective? Could someone please confirm that he became a stronger player by using that method of studying?

# Answer
> 6 votes
I'm only a 1600 so take my advice at face value

I hear a lot of people saying all the time not to waste their time on openings, just focus on tactics and endgame. That advice is nice and everything but if you never make it out of the opening the endgame is worthless. I had a game in a tournament where I fell for Lasker's trap in the Albin-Counter Gambit. If I had spent just 5 minutes studying that line I could have avoided that and survived to use the lessons I have studied in the endgame.

I guess what I am trying to say is that instead of thinking of it as "should I do one or the other" you are going to have to do both. If you want to get good you can't avoid any one area you are going to have to give them all attention. Studying openings leads to a strong positional understanding and leads to understandings in similar openings. For instance understanding the sveshnikov sicilian helps with understanding the themes in the kalashnikov.

Study a lot of tactics because every 2000+ I have heard has said tactics are what you need to know. Hope this helps

# Answer
> 6 votes
Endgames are the most powerful way to learn tactics, properties of the pieces, visualization, and calculation. Anyone who thinks they're boring should thumb through a few pages of Van Perlo's Endgame Tactics. You'll be amazed at the creativity, surprises, and overall amazing capabilities of just a few pieces in the hands of a capable player.

What's more, in the middlegame you have pawns shielding and supporting your pieces, and have enough pieces that most or all are always defended. In the endgame, pawns are diminished or scattered, and you only have a couple of other pieces to work with. You *have to* go out on a limb and leave your pieces loose once in awhile, and the winner is often better at judging when you can get away with this and when you can't, and does more of it, more successfully.

By the way, this means that you should understand some of the strategies for each type of middlegame you're likely to come across, but don't focus on theory all the time. Look at practical endgames from a database, and analyze them.

Get a few openings (1 for White, 1 each for Black against 1.d4 and 1.e4) that you feel comfortable playing. You don't need a backup rep unless you're playing both standard and blitz time controls (you can play much riskier stuff in blitz), until you hit about 1800-1900 ELO.

# Answer
> 4 votes
You learn them at the same time. Endgames and Openings are not subjects that you can learn overnight. It can take a strong Grandmaster years to master the endgame phase.

It's the same way with openings; simple guidelines and principles should be learned at the beginner, but strong players \> 2000-2200 should know heavy opening theory.

So when you **first start** playing chess, openings and endgames will not be the decisive factor in your games. You should learn the opening principles and guidelines: `don't move the same piece twice unless there is a tactic`, `control the central squares`, `don't block your c-pawn on c2 in d4 d5 openings`, and so on. It even helps to know some simple opening lines, e.g. 1 e4 e5 is the King's pawn game. 1. d4 d5 2.c4 is the Queen's Gambit.

Similarly, start with the simple endgames. Checkmate with King and Rook, checkmate with King and Queen. Also you learn simple pawn endgames, King and Pawn versus King. How do you promote a pawn, if you can? How do you stop the pawn and get a draw, if you can?

Then when you get to about **1500**, when you don't make a lot of material blunders, it makes sense to increase your opening knowledge. Learn lines to about 10 moves deep in a few openings that you play, especially the main lines.

At 1500 learn the simple King and Rook and Pawn versus King and Rook endgames, like the Lucena and Philidor positions. It also helps to have some familiarity with Knight, Bishop, and Queen endgames. However *theoretical* endgames and openings still will not decide your games. Strategy and positional skills, as well as your technique (ability to convert a positional advantage into a point) will.

When you get to a high level, say **1900-2200**, your games will be impacted more and more by opening knowledge and endgame skill. Then it makes sense to be an opening and endgame expert.

# Answer
> 4 votes
Here's my take on it. Listed according to priority:

a) Simplest end-games (RK vs K, QK vs K, BBK vs K, KP vs K)

b) Opening that you are interested (at-least one as white and at-least two as black). Find out first five moves in the opening and what are the general strategies and plans in that specific opening. Guidelines on where pieces are generally placed in the opening and typical pawn formations.

Why I place this as the second important step is that you will never enter an end game with equal chances, if you don't know the opening even this much.

c) Complicated end-games (KPP vs K, KPR vs KPR etc., the whole load of it)

d) Deep opening prep - if you reached this step that is :)

# Answer
> 4 votes
I agree pretty much with Keshav with some minor additions. When I taught my kids I started out alternating between the basic endings and playing a game with just the pawns where first person to queen wins.

This brings up another very important point. You will get best value with an opponent sitting opposite you when you are doing much of this learning / studying, even if it is the computer. Moving pieces on a board rather than doing it in your head is important.

After basic endings and playing with pawns I'd follow Keshav with the first few moves of several basic openings coupled with some basic opening principles like get out a center pawn, move the knights and bishops towards the center, castle, etc.

Before more complicated endings I would put tactics. Pins, forks, skewers, removing the defender, etc.

Assuming you have already mastered the basics, basic endings, pawn play, basic openings, simple tactics, then I would suggest the biggest bang per buck will come from heavy tactical work. Get some of those tactical puzzle books and just work through a dozen or so problems a day. If you can't see the answer on the page then set the position up on a board and move the pieces if you have to.

Longer term keep those daily tactical puzzles going and add work on more difficult endings like KPvK, KRPvKR, KBNvK. Learn the theory, practice both the attack and the defence with a real board against an opponent.

As your play improves and your standard of opponent improves you will need to work on your opening repertoire to make sure you get out of the opening with a good game and plenty of time left on the clock.

# Answer
> 3 votes
It's very difficult for a beginner to study endgames because they think like, "what good does it do to study endings if I get killed in the opening and middle game." Of course this is logical in its own way and I would suggest tactics, tactics, tactics first. However here's a reason for studying endgames that I feel really helps. You really learn the power of the pieces. For example if you study an interesting R+p vs R+p ending you will learn how great the Rook is at defense or its power to attack and defend simultaneously. You start to admire the power of Bishops and learn their weaknesses. You'll discover the power of a well posted Knight or its weakness in stopping rook pawns. These are all concepts that are easier seen with fewer pieces on the board, i.e. endings. Something to think about as it will rollover into your middle game planning. Suddenly you'll look at games (another must is to play through many games) and understand the positioning of pieces, exchange of pieces, pawn structure etc etc.

# Answer
> 3 votes
`Could someone please confirm that he became a stronger player by using that method of studying?`

I can confirm, I was 2000-FIDE, struggling to beat players of the same rating. After a month of serious endgame study, I increased my rating to 2200 fairly quickly. Since then, I am continuously studying endgames.

A lot of players at that level have a gap in their knowledge of endgames, which becomes especially visible when they are low on time. By studying endgames myself I scored a lot of extra points by winning equal or holding lost endgame positions.

So if you're at level 2000 or lower, I would advise to **focus** on **studying** endgames at your own time and refresh your knowledge on openings/strategy/something else while playing in tournaments.

Some arguments for studying endgames:

* Concrete evaluation. The position is a win/draw/loss with a clear explanation of why. This helps to build a rigorous understanding of the game. Contrast that with the phrase `in this opening white is slightly better` with a subjective explanation.
* Everlasting knowledge. You learn once that the Lucena position is winning and this fact remains true forever. Now contrast this with a belief that `the Exchange Caro-Kann gives black an equality` until someone finds a new idea how to play for an advantage with white.
* Useful in practice when you're low on time. Even if you don't know the opening, you can spend a lot of time and come up with a decent move (not necessarily the best). In the endgame, you will be down to your last seconds. It's very unlikely you will find an accurate move with few seconds remaining by yourself - even the top players do not always find!

# Answer
> 2 votes
Yes,

because a won endgame is ending in a checkmate, and you have to learn how to checkmate first.

However,

Fischer's famous chess teaching book does not even start with an endgame but with mate-in-1 positions. Polgar (the father of the three chess sisters) also uses this method. I think it is superior to endgame training.

# Answer
> 2 votes
Endgame study seems boring especially for novice players, but it's necessary for two reasons: you need to know what is winning and how, and more importantly IMHO it helps you internalize the basic tactics of these pieces.

That said, I can tell you certainly when I was 1900 to mid 2100 USCF, the majority of my wins from lower rated players, and the easiest, arose from exploitable opening mistakes. You have to do both. Not just five moves and a general idea of where the pieces go. but familiarize ourselves with the associated lines as much as possible. It is much better to know one or two openings pretty well than to try to learn a bunch halfway.

To answer your question explicitly, yes when I was 15 (rated around 1550) I got a hold of an endgame book and went through all of the positions, every chance I got. At that time and that place there were no strong local players so I had to play in tournaments to improve, ten or fifteen games per year. So there are better ways to train, but left to my own devices I feel like that was the first step in improving.

# Answer
> 1 votes
I like to think of chess as a journey. You have to know your destination before you can decide how to proceed. Unless you know how to win a simple endgame, you'll have no idea how to set the course of the game. Of course games can end earlier, but usually that's due to some tactical mistake. If you can achieve a small advantage and transition into an endgame with that, you'll know how to convert it into a win. Study the basic piece endings first (K & R vs K; K, B & B vs K, etc.) and then study the K & P vs K endings (learn the "opposition" and "triangulation") as well as K, R and P endings and you'll be in good shape when you reach the endgame. It has made a big difference in my game, for example allowing me to win a tournament game where I had a K, B & N opposed to the lone K as well as recently a K & R vs K & N ending. And when I reach K and P endings, I no longer feel unsure of myself as I once did.

---
Tags: learning, endgame, strategy, positional-play, training
---


# Question
Title: Can you move from one side being checked to other side in stalemate?
I am not a chess player but I have a homework where I have to code a chess program. I would like to know if it is possible for a player's piece to be in check, the player to move out of check, and in turn put the other player in a stalemate, from just one move?

For example: White is in check -\> White moves out of check -\> Black is stalemated

I haven't found any examples of it so far, but I also haven't found anything saying it's never possible, so if anyone can say either way that would be great!

# Answer
It's possible, e.g.

```
[FEN "2Q4k/2R4b/8/8/8/8/K7/8 b - - 0 1"]

1...Bg8+
2. Ka3?? 1/2-1/2

```
> 4 votes

---
Tags: programming, check, stalemate
---


# Question
Title: Formulating a Precise Definition of "Space" in Chess
**Premise**

I have always enjoyed playing recreational chess, so I know the basics and some general tactics / strategies. It was only recently though that I have gone more hardcore, so to speak, with my analysis. Namely, I'm taking the "big data" approach by looking at the freely available game logs (which contain hundreds of thousands of games).

I realize there has already been expert machine-learning analysis done with this data and some of it published. However, I'm doing this just because I like chess and I like to dabble with programming. I don't expect to win any Nobel prizes, but I do expect to have fun along the way. Basically I think it's cool to test out the theories or rules of thumb for their effectiveness. Like I said, I'm trying to be humble/realistic about my model specification, and there are probably some things I cannot capture from the data. Some variables/features are easier to formulate than others; which brings me to my question.

I'm trying to figure out if I can create a variable (aka feature) for which player has more "space." Let's say we have this position:

White is said to have a space advantage here. Maybe it's my lack of expertise, and I'm not sure exactly what "space" is being referred to here; I see a few different things going on. The following are my three attempts to explain "space." (bear in mind I am aiming to reduce "space" to something quantitative, hence the nerdy-sounding explanations)

* White's pieces have a shorter average distance to the end of the board than black's. White's pawn is all the way on the 5th rank, while black's pieces are closer to his starting position
* White has more available moves. Black is looking rather cramped, some of his pieces are getting in the way of each other.
* White controls more squares. White's light square bishop controls a longer diagonal than black's, and so forth.

This is the confusing part for me, because I could easily rationalize any of the above items as being "space." Citeris paribus, we could expect a correlation between some of these things, but eventually I have to settle on a precise definition of "space" if I'm to transform chess logs to a quantitative variable.

**Question:** Is there a precise definition ( be it in the literature or an unspoken but widely understood axiom) of the concept of "space?" Perhaps none of my attempts to explain space are close, and there is a 4th better definition. Either way, please feel free to weigh in.

**Note:** All I'm asking is a precise definition. You do not have to reduce your definition to the quantitative (unless you want to!)

What is 'space' on a chessboard? the accepted answer to this post hints at my 2nd definition: "space in terms of the number of possible legal moves you have." Is that the overall consensus though?

# Answer
> 3 votes
Considerations such as yours for a definition of "space" have long been a part of computer chess, and I suggest looking to that literature for ways to approach a precise, quantitative definition. The ideas you already outline in your list touch on things like piece mobility and control of squares (and in particular, the center) that generally go into the evaluation by engines of who has, in some sense, more space.

You write, of your distinct starting points, "I could easily rationalize any of the above items ... we could expect a correlation between some of these things, but eventually I have to settle." I would stress that **you don't actually have to choose** from among these as though they are distinct, opposing alternatives. Rather, just as engine evaluations take myriad considerations about material, space, king safety, etc. for a given position and boil it all down to a single numerical value, the same can of course be done for just the "space" component of things, making a composite score that simultaneously reflects e.g. the relative mobility and the relative square control of the two sides. Again, I would recommend looking at how these things are actually implemented in engines, and to go from there.

# Answer
> 2 votes
I define space as a mixture of mobility and squares controlled.

```

[fen "rbk3br/2p2p2/1pP2Pp1/pP4Pp/P6P/8/4R2K/4R3 w - - 0 0"]

```

Black is completely lost due to his lack of space.

```

[fen "8/2p2p2/1pP1kPp1/pP1rr1Pp/P6P/2K5/4R3/4R3 w - - 0 0"]

```

Black is just as cramped, but his greater mobility and more active king gives him a much better game.

EDIT: From "Elements of Positional Evaluation" by Dan Heisman. Section 3.3 Space

So to better understand space, we must once more return to mobility. What is important to realize is that space depends on mobility; that is, mobility "defines" space. This means that no matter how the pieces are situated, the player with more space is really the one with more actual and actual global mobility, despite what the pawn structure may seem to indicate. For example, in a closed position where White's pawns seem more advanced, if Black's pieces, through open files or diagonals, can "point" through and around the pawn mass in some way that gives Black the superior actual mobility, then it is he who may seem to obtain the space advantage. This is additionally made posible because pieces are not legally bound to stay behind either side's pawns. Indeed, an over ambitious early push of a pawn mass somethimes leaves one's pieces scattered to the defensive at some later time because the opposition was not effectively reduced in total actual mobility and god behind the advanced pawns. So, whereas space is an existing and useful term, it does not qualify as a basic element.

# Answer
> 1 votes
From a human, chess player perspective, *space* is something you talk about in opening/middlegame (rarely in endgames), when there are many pieces on the board. In most normal openings it is typically determined by how far up the board you moved your pawns, particularly the central pawns. Think about something like the advance French variation, where white has more space, because he has got a pawn on the 5th rank, while black did not move any pawn beyond the center of the board.

By moving the pawns further than your opponent, you gain more "space" for operating your pieces, i.e., the number of possible moves should increase. Conversely your pawns might very well limit your opponent's options, not necessarily the number of legal moves, but the number of moves that don't lose material.

As you want to do this automatically, I believe that checking how far the pawns moved is not a good measure for space, because you would have to distinguish between central pawns and others, and also some pawn structures might be more effective in creating space than others.

Number of legal moves, could be a measure, but I would suspect that this might not be very sensitive, because even in your example the difference might be small.

If you don't mind the calculation overhead, I would suggest **number of legal moves that do not lose material immediately** as a measure. This would take care of the fact that the player with less space is limited in developing options, because attractive developing squares like (for black) f6, c6, d6, e6, might be under attack by pawns.

I'd also experiment with ignoring moves on the 1st/8th rows.

# Answer
> 1 votes
One definition that I've seen, I believe it was in Larry Evans' book, *New Ideas in Chess*, but it may have been another book, is that the amount of space one controls can be determined counting the number of squares you directly attack on your opponents side of the board.

In the position shown, white's space count is 8, and black's is 2. White is directly attacking b5, c5, d5, e5, f5, g5, c6, and e6, while black is only attacking d4 and f4.

# Answer
> 1 votes
I believe that we can "visualize" the space, as the area of the board that is available to each player to safely maneuver their pieces because it is the area they control.

In my opinion, an easy way to count how much space corresponds to each player is to add the squares behind the pawn lines in which the pieces of their color can move, plus the squares controlled by the pawns in which the opponent can not recapture immediately with a pawn.

Thus, the player with black pieces has, for example, eight squares behind the pawn line, plus four squares that attack his pawns without the opponent having pawns that they can immediately recapture. A total of twelve squares (12 = 8 + 4).

Instead, the player with the white pieces has twelve squares behind his pawn line and his pawns control seven squares. A total of nineteen squares (19 = 12 + 7).

A difference of seven more squares in favor of the player with white pieces.

---
Tags: analysis, theory, programming
---


# Question
Title: Some strange moves in Polgar vs Najer (2009)
In the 2009 match between Judit Polgar and Evgeniy Najer in Richard Riordan GM Blitz the following strange(?) opening sequence of the Najdorf was played

```
[White "Judit Polgar"]
[Black "Evgeniy Najer"]
[Result "1-0"]
[fen ""]

1. e4 c5 2. Nf3 d6 3. d3 Nf6 4. d4 cxd4 5. Nc3 a6 6. Nxd4 e5 7. Be3 Be7 8. Nb3

```

Black refuses to take the white knight on both move 5 and 7 but why? I see no horrible threat if the capture is made.

# Answer
> 9 votes
The game Najer - Polgar, Richard Riordan GM Blitz, 2009 is from TWIC 767, along with the above sequence of moves. Sicilian Paulsen, White win, 78 moves. There are a large number of moveless games from the same tournament, so it looks like the event organisers had problems recording the game moves accurately.

# Answer
> 1 votes
I'd bet a lot of money that somehow one move from either side was stored incorrectly which makes the whole game incorrect.

A possible correct version of this game may be 1.e4 c5 2.Nf3 d6 3.d4 Nf6 4.Nc3 cxd4 5.Nxd4 a6 6.Be3 e5 7.Nb3 Be7 Or some other permutation of those moves (e.g. play 4...cxd4 one move earlier, I chose this order since it's closer to the game given).

The cause for this probably was some kind of error with the DGT board transmission.

---
Tags: opening, analysis
---


# Question
Title: An interesting eight pieces Queen endgame
Looking at a human game between strong players, one of the variations reached the following endgame WHITE to move.

```
[FEN "4Q3/8/2pK4/1p6/1P4k1/P7/8/7q w - - 0 1"]

```

Since Qxc6 is a draw (Lomonosov tablebases) is the endgame a draw? Or there is a sophisticated win for White in some way, maybe submitting the black King to a barrage of checks? Since my engine does NOT have tablebases incorporated into it I am in the complete dark. What does FinalGen say about this endgame?

# Answer
Stockfish with tablebases gives flat 0.00 so it seems highly likely to be a draw. A problem for White is they can't even take the c6 pawn with the king, 1.Kc7 Qh2+ 2.Kxc6 is a draw. So since Black can just keep giving checks and force the white king on awkward squares this seems hard to ever be winning. (especially since Black can always threaten to pick up the a3 pawn making an immediate draw)
> 2 votes

---
Tags: analysis, endgame, queen-endgame
---


# Question
Title: How many moves needed to reach this position?
"Homebase" is where all the surviving pieces are apparently on their starting squares. Here is a very easy new example proof game: can you find the unique shortest game that leads to this position?

```
[Title "A.Buchanan 26-11-2020: shortest proof game?"]
[FEN "rnbqkbnr/ppppppp1/8/8/8/8/PPPP1P1P/RN2K1NR w - - 0 1"]

```

Yes c1 is empty!

# Answer
> 4 votes
I have no idea about this kind of problems, but my guess would be something like this.

```
[FEN ""]

1. g4 h5 2. Bg2 hxg4 3. Bf3 gxf3 4. Kf1 fxe2+ 5. Kg2 exd1=R 6. Kf3 Rxc1 7. Ke2 Re1+ 8. Kxe1

```

Is that unique? I have no idea.

# Answer
> 2 votes
For a partial answer, here are a semi-unique sequence sin 11 moves. They are no doubt revealing of the true solution's strategy.

```
[FEN ""]

1. e4 h5 2. Qxh5 Rxh5 3. g4 Re5 4. Bc4 Rxe4+ 5. Kf1 Re1+ 6. Kg2 Rxc1 7. g5 Re1 8. Be6 Rxe6 9. g6 Rxg6+ 10. Kf1 Rh6 11. Ke1 Rh8

```

Or this.

```
[FEN ""]

1. e3 h5 2. Qxh5 Rxh5 3. g3 Rh3 4. Bd3 Rxg3 5. Kf1 Rxe3 6. Kg2 Re1 7. Bf5 Rxc1  8. Bg4 Re1 9. Bh3 Re3 10. Kf1 Rxh3 11. Ke1 Rh8

```

And this.

```
[FEN ""]

1. e4 h5 2. Qxh5 Rxh5 3. g3 Re5 4. Bh3 Rxe4+ 5. Kf1 Re1+ 6. Kg2 Rxc1 7. Kf3 Re1  8. Kg2 Re3 9. Kf1 Rxg3 10. Ke2 Rxh3 11. Ke1 Rh8

```

---
Tags: problems, retrograde-analysis
---


# Question
Title: How to solve this puzzle of Martin Gardner?
Martin Gardner mentioned the following "chess" problem in his column, *Mathematical Games*, for Scientific American (he got it from Smullyan, who learned about it from a high school math teacher):

> ... Assume that a game is played with the new rule that a knight can on a single turn move twice. It is not clear if this more powerful knight move is an advantage to the first or second player. The first player, White, offers to play the game without his queen. How can he be sure to win?

After thinking a bit, I could not make progress, so I look at the solution:

> White jumps queen's knight forward twice. Checkmate!

That's all it says. How is this a checkmate? I must be missing something.

# Answer
According to the FIDE Laws of Chess:

> 1.4 The objective of each player is to place the opponent’s king ‘under attack’ in such a way that the opponent has no legal move.
>
> 1.4.1 The player who achieves this goal is said to have ‘**checkmated**’ the opponent’s king and to have won the game

That means that if white has a knight which is 2 normal knight moves away from the opponent's king then the opponent's king is in check, under attack.

Then consider white starting the game like this:

```
[fen ""]

1. Nc3 null 2. Nb5

```

Then you can see the black king is in check. On the knight's next move it can go Nb5-d6-e8. But there is no way for black to get out of check. Hence it is checkmate.
> 13 votes

# Answer
Ok, I think I got it. Your first move is Nc3-Nb5, threatening Nxc7 and Nxe8 in its next move, and since Black can't move their King they just can't prevent check mate.

EDIT: just to make it clearer, actually the first move is Nc3-Nb5+, since the Knight is attacking the king because of the special way it moves.
> 4 votes

# Answer
I guess that can White play 1. Nb1-a3-b5+ or Nb1-c3-b5+ or Nb1-a3-c4+, in order to be in range of the bK but not in range of the bKN.

I suppose we clarify that if the first knight move is a capture, the second move can still take place. Otherwise 1. ... d6! defends.

But what happens if the first knight move is a check? Does that mean that White doesn't get to make a second move? And does that affect the definition of check. Because wNb5/wNc4 cannot threaten to capture bK, as the first move wN-d6+ checks bK and that would terminate the turn!

If this is correct it means that a knight only gives check when one move away from bK. Can the original poster make clear how this works, please?
> 1 votes

---
Tags: checkmate, problems, puzzles, mathematics, unorthodox-pieces
---


title: A cramped opposite color Bishop endgame

text:
# Question
Title: A cramped opposite color Bishop endgame
From **"Modern Endgame Manual"** by *Mikhalchishin*, the following position is analysed and determine to be a winning position for White.

Is Mikhalchishin's analysis correct or does the defensive capabilities of modern engines make this a position a draw?

```
[Event "Russian Championship Higher League"]
[Date "2013.06.23"]
[White "Boris Grachev"]
[Black "Daniil Dubov"]
[Result "1-0"]
[ECO "D47"]
[WhiteElo "2683"]
[BlackElo "2638"]
[FEN "1b4k1/p4p1p/5p2/2P1pB2/8/8/P4PPP/5K2 w - - 0 33"]
[EventDate "2013.06.19"]

```

# Answer
> 1 votes
The analysis of this position seems quite reasonable based off an immediate glance of the board. Grachev has the advantageous position as he is first to move in this position which is essential for this end game play out. The c5 pawn is key to Grachevs success and without playing out the whole game immediately moving to defend it with the King is the most route to success. Dubov is incapable of promoting on the King side of the board and the double pawns do provide somewhat of a hinderance to Dubovs position.

This is effectively how the game rolled out to my understanding of it, Grachevs king charged at the c5 pawn, Dubovs and Grachevs Bishops began gobbling up pawns and White ultimately used the king to progress the queen side pawns on the A and C file to the point Dubov resigned.

In regards to the definitively analysing with modern engines. Using Komodo Dragon against itself for 10 games, in all 10 games White won. In this position, white is better in all key lines ranking from +3.53 (in the best line for White) to +1.4 in the worst line.

# Answer
> 0 votes
Being played by good players, it sure looks like a win for white but it will take some work.

In real life anything can happen especially depending on the clock situation. And it depends on how hard white wants to work to get that extra half point.

And in positions like this there could often be a hidden gotcha that is not obvious until more moves are played so it could be a draw.

---
Tags: bishop-endgame
---


# Question
Title: How did a pawn appear out of thin air in “P @ e2” after queen capture?
I was playing chess against the computer and captured black’s queen. All of a sudden, a black pawn appears out of thin air, one space behind the captured queen for a total of nine pawns, and moves multiple squares diagonally.

The computer calls this move “P @ e6,” but after half an hour of scouring the internet, I could not figure out what that means.

```
1. |  h2 - h4 | Nb8 - c6 |
2. |  e2 - e4 |  e7 - e5 |
3. | Rh1 - h3 | Qd8 × h4 |
4. | Rh3 - h4 |   P @ e2 |

```

How did this happen?

# Answer
> 29 votes
You were playing the chess variant called Crazyhouse. In this variant you can place pieces you captured, as one of your color anywhere on the board, instead of a normal move.

I don't know the software you are using, but on Lichess the variant can be selected in the "Create a game" dialog. There should be something similar in your application.

---
Tags: rules, pawns, captures
---


title: A historical computer chess endgame

text:
# Question
Title: A historical computer chess endgame
In Season 11 Superfinal Game 78 the following opposite color Bishop endgame was reached:

```
[FEN "8/2p1k3/1p6/p4B2/P2P1bP1/2P5/1P3K2/8 w - - 0 1"]

```

In that Superfinal Stockfish smashed Houdini 20 wins versus 2 , but this endgame is interesting because , if Stockfish ( black) did draw it would have completed the Superfinal with a record of only one loss. I am not certain because the tabulates indicated Stockfish was in time trouble at this juncture of the game. Is the endgame a win or a draw? I ask to look (at least) past depth 48.

# Answer
> 3 votes
I didn't put any effort into this however just letting the engine search, it seems to be winning for White, evaluation steadily rising:

```
[FEN "8/2p1k3/1p6/p4B2/P2P1bP1/2P5/1P3K2/8 w - - 0 1"]

1. Ke2 c5 2. Kd3 cxd4 3. cxd4 Kd6 4. Kc4 Bh6 5. Be4 Bd2 6. Kb5 Kc7 7. Bh1 Be3 8. Kc4 Kd8 9. Bd5 Ke7 10. Bg8 Kd6 11. d5 Ke5 12. Kb5 Kd6 13. Bf7 Kc7 14. b4 axb4 15. Kxb4 Kd6 16. Kc4 Bf4 17. Bg8 Bc1 18. Kb4 Kd7 19. Be6+ Kd6 20. Kb5 Be3 21. Kc4 Bf4 22. Kd4 Bg3 23. Bc8 Ke7 24. Kd3 Bd6 25. Be6 Bh2 26. Kd4 Bf4 27. Ke4 Bg5 28. Kf5 Bd2 29. g5 Bc1 30. Bc8 Kd6 31. Bb7

```

+- (6.25 ++) Tiefe: 57/53 00:45:26 8834MN, tb=31896574

You can get the current version of Stockfish here https://abrok.eu/stockfish/ , then you can run your own searches.

---
Tags: engines, endgame
---


# Question
Title: Is short castling dangerous in Bughouse?
When I play Bughouse, I see that, every single time after a castling, petty sacrifices can easily be break the wall that surrounds the king,Therefore, is it really worth castling, especially short castling, in Bughouse?

# Answer
Tempo is king in bug house for castling. By definition, unless your castle makes a immediate threat somehow, you have lost 1 tempo. In other words, it is at least one more move until you improve or gain position to attack.
If it takes your op 2 or more moves to make a threat, then you have a +1 tempo gain and it might be worth it. If you are under immediate threats, then this might be good also if it forces a 1 tempo action for op to retarget.

If your partner's board is timelocked, then it may be of long term value to castle. Depends on how many troops are waiting to crash down. Your board becomes more like a normal yet rapid chess game
> 6 votes

# Answer
It is certainly believed by many that castling is a "bad" move in bughouse (and if king side castling is weak, queen side in my experience can be much worse). But I have seen world class (2500+) BH players castle either side, probably more commonly k-side.

One of the chief ways in which a castled king (on the king side) is attacked is via the H pawn and it is clear that defending that pawn is harder than most squares: The king protects it but that is surely not a very good protector because of course if the pawn is taken, the king is now on H2 or H7 and then is subject often to a mating attack. Since the H pawn is at the edge of the board, there are no squares to the left (or right if you are white) of it on which to place protectors. So basically H2/H7 is a very weak square and the poor king is right next to it.
> 3 votes

---
Tags: chess-variants, castling, bughouse
---


# Question
Title: Is targeting the f7/f2 square in bughouse a good rule of thumb?
In Bughouse, players often target the f2/f7 square; it is common to see a minor sack on f7, followed by a knight on g5 delivering check and breaching through the opponent's defenses.

I recently played a Lichess Bughouse game where, even though the opponent castled, the f7 square still offered opportunity.

Personally I think I'm still novice with bughouse, so I'm wondering if just attacking the f2/f7 square is a good rule of thumb. Or, is there is some better general advice for beginner or intermediate players to follow?

# Answer
> 4 votes
https://www.youtube.com/channel/UCcKXwA\_lo3Zpz3\_Mc-WVLtw is the YouTube channel of Helmsknight. She is a strong player who plays with Nakamura, Seirawan, and many other high rated players. Interesting is that all these players tend to castle before starting an attack.

Just like normal chess, starting an attack on this (these) square(s) is often a good idea. However, I used to take advantage of this common attack and have both boards play passively. Soon my opponents would be down a couple of pieces (on each board sometimes) and no resources to continue the attack.

For a better understanding of proper use of resources, Crazyhouse is the variant.

# Answer
> 2 votes
In general it's a good idea, but to every rule there are exceptions. For example, if your opponent's king is safe (such as from castling) and he has lots of pieces around defending, sacrificing the knight on f7 may not be a good idea.

# Answer
> 0 votes
I am convinced that saccing a bishop (but not a knight) against opponent's KB2 (to use the old notation which works better when discussing BH sometimes) is reasonable simply because 1. a bishop is not that valuable in BH 2. your partner gets a pawn that can be plopped down anywhere and sometimes a pawn, placed on the 7th rank, is better than placing a B there.

But would 4 world class players play differently because the sac is basically unsound and the loss of the bishop is too much if the opponent defends right? I am not world class but I sure see top players making this sac against my team -- maybe if my rating was 300 points higher, they would not.

---
Tags: sacrifice, attack, bughouse
---


title: Is 1. Nf3 good for white in bughouse?

text:
# Question
Title: Is 1. Nf3 good for white in bughouse?
When my friends and I play Bughouse, a very common opening we play is `1. Nf3 Nf6, 2. Ng5 Ng4, 3. Nxf7 Nxf2, 4. Nxd8 Nxd1` .

```
[FEN ""]
1. Nf3 Nf6 2. Ng5 Ng4 3. Nxf7 Nxf2 4. Nxd8 Nxd1

```

Is this a good choice of opening in Bughouse?

# Answer
> 7 votes
For an opening to be good in bughouse, it needs to incorporate both boards. Timing, material trades, attack/defend all have a huge influence. On top is predictability. If you know what the ops will try, then you may come up with a counter.

For example, 3 ... KxN is playable by black if there are limited material and a huge flood does not come on board. If the other board can control the flow of pieces then this sac will fail. Yes, KxN could get hammered if several drops come into play. But look what the other side gets. A drop knight vs a drop pawn. No immediate easy path to getting more pieces. Most likely a time bulge. (Typically one player waits for pard to get them stuff to drop on the exposed king.) With enough of a time lead, the off board can wait and force you to play a few moves without extra stuff.

As part of team opening, the knight sac can be useful, but need to first gain enough drops to make it a threat. To do this, will need play on other board to be faster, and get 3 or more drops in hand.

# Answer
> 1 votes
`1. Nf3` is a bad move in bughouse. `Nf3` intending to `Ng5, Nxf7` is not good because this idea can be easily refuted.

```
[FEN ""]
1. Nf3 e6 2. Ne5 Qf6 3. Nxf7 Qxf7

```

Place the knight on `g6, Qe7`, pawn on `f7, Kd8` and *Black king is surprisingly safe*.

There are many other good options for White such as `1. e4`.

# Answer
> 1 votes
I don't think nf3 is bad at all but the multiple moves to sac on f7 is using up too many tempi and also giving up a knight is different than saccing a b. i think against any team over 1500 or so a team on which white plays this opening would lose pretty consistently. a tempo is a very valuable thing in standard chess and probably more valuable even in BH.

---
Tags: opening, chess-variants, bughouse
---


# Question
Title: Famous grandmaster games of "torturous" winning or flaunting out of arrogance?
I was originally wondering why we don't see more torturous type of games among masters. For example, instead of proceeding to checkmate, the player in control methodically takes all pieces of his opponent before ending the game. This would be a more gratifying experience, especially if there was bad blood between the players. Then it dawned on me, that at the master level, a player usual resigns as soon as he knows he lost competitive influence on the outcome of the game, thus he avoids subjecting himself to that kind of "punishment." But chess has a long history and perhaps I'm wrong and there is actually a few good instances of tortuous winning.

## Question

Are there such examples of torturous winning, where a grandmaster resists his urge to resign and lets the opponent take all of his pieces before he gets checkmated? Perhaps taking every piece before checkmating is extreme, I would also accept answers that could show a famous grandmaster game where a winning player exhibits "arrogance."

# Answer
> Are there such examples of torturous winning, where a grandmaster resists his urge to resign and lets the opponent take all of his pieces before he gets checkmated?

No, there aren't, for the simple reason that that sort of behaviour would require both players to behave in an extremely childish manner and childish behaviour (e.g. "hope chess") is something you have to eliminate to become good enough to become a grandmaster.

The aim of the game is to checkmate the opponent, not take all their pieces. Good players understand this. All grandmasters are very good players. Delivering checkmate gives most adult players and all strong players far more pleasure than taking all the opponent's pieces.

What you do see sometimes amongst strong players, including grandmasters, is the player who is defeated by an unexpected tactical blow, which leads inevitably to checkmate, allowing the checkmate rather than resigning when it becomes clear what has happened. This is seen as particularly sporting behaviour. Normal behaviour would be to resign once it becomes clear. Spiteful behaviour would be to resign one move before checkmate.
> 18 votes

# Answer
I think you will find plenty of examples of such games, in time-controlled games where it is in the interest of the losing player to keep playing for three reasons:

1. To try and flag the winning player on time - winning.
2. Time pressure could cause your opponent to blunder
3. To try and salvage a draw through a stalemate.

Eric Rosen who streams on youtube is one of those players who never accept draws and I don't think I've seen him resign in time-controlled games. He is famous online for "The Rosen Trap" where he gets his opponent to blunder a winning position into a drawn stalemate: https://www.youtube.com/watch?v=NsKjIkYiiOA

On a side note: I once played a much higher rated player in a 5 or 10-minute game and he was up 1 or 2 pieces, expecting me to resign (I think) and when I didn't he proceeded to block in my king, and promote each and every pawn of his into knights, then moved his knights\[horses\] back to his side of the board - in effect building himself a ranch. Like a cowboy. I did not manage a stalemate.

But those types of games are usually not a good source for learning material - except of course if you want to teach to never give up, never give in!
> 5 votes

# Answer
Probably not what you're looking for, but you might still be interested in this game.

```
[FEN "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1"]
[White "GM Andrew Tang"]
[Black "Leela Chess Zero"]

1. d4 Nf6 2. c4 e6 3. Nc3 d5 4. cxd5 exd5 5. Bg5 Be7 6. e3 O-O 7. Bd3 c5 8. dxc5 Bxc5 9. Nge2 Be7 10. O-O Nc6 11. Rc1 h6 12. Bf4 a6 13. h3 Be6 14. Bh2 d4 15. Nxd4 Nxd4 16. exd5 Qxd4?? 17. Bh7+ Kxh7 18. Qxd4 Rad8 19. Qe3 Rfe8 20. Ne4 Bxa2 21. Nxf6+ Bxf6 22. Qf3 Bxb2 23. Rc2 Bd5 24. Qd3+ Be4 25. Qb3 Bxc2 26. Qxc2+ Kg8 27. Qxb2 b5 28. Be5 f6 29. Bxf6 gxf6 30. Qxf6 Rf8 31. Qg6+ Kh8 32. Re1 Rd7 33. Re6 Rg7 34. Qxh6+ Kg8 35. Rg6 Rxg6 36. Qxg6+ Kh8 37. Qxa6 b4 38. Qb6 b3 39. Qxb3 Rf7 40. Qg3 Rg7 41. Qxg7+ Kxg7 42. g4 Kf6 43. Kg2 Kg5 44. Kg3 Kg6 45. f4 Kf6 46. h4 Kg6 47. g5 Kh5 48. Kf3 Kg6 49. Kg4 Kg7 50. h5 Kh7 51. f5 Kg7 52. f6+ Kf7 53. Kf5 Kf8 54. g6 Kg8 55. Kg5 Kh8 56. Kh6 Kg8 57. g7 Kf7 58. Kh7 Kxf6 59. g8=Q Kf5 60. Qg6+ Ke5 61. Kg7 Kd4 62. h6 Ke5 63. h7 Kd4 64. h8=Q Kc4 65. Qhh5 Kb4 66. Qgg4+ Kc3 67. Qhh3+ Kb2 68. Qgg2+ Ka1 69. Qhh1#

```

Writeup of the match including this game.

Of course, this game only went on as long as it did because:

1. It's ultrabullet. With 15 seconds on the clock you go for the guaranteed mate, not the fastest one.
2. Leela's a chess engine. It won't resign if it's not programmed to do so.
3. Humans should savour any opportunity they get to humiliate computers =)
> 2 votes

---
Tags: history, psychology, grandmaster, famous-games
---


title: Library to program mini games

text:
# Question
Title: Library to program mini games
In Corona times, it is not so easy to train children over the board. When that was possible, we used a lot of mini games with fewer pieces and most of the times a different goal. To bring those mini games online is not so easy, due to many factors:

* Known chess libraries like `chess.js` (the most used Javascript library for chess) only allows standard games and does not support mini games.
* Chess online sites like lichess.org have their set of games possible, and it is not at all easy to expand that.
* Children should have a very simple web interface to start a game, play it, ...

So I am thinking about creating something myself. I am sure I can come up with a simple web application to register, pair players, ..., but the hardest part (for me) is to check that the rules of chess are met. But this set of rules is not fixed. Here are some examples

* Some mini games don't have kings at all. This is not allowed in standard chess.
* Some mini games treat the kings like normal pieces, so there is no chess, or even kings can be beaten.
* Some mini games define the end of the game when the first piece is beaten. Or a pawn is promoted.
* One variant I know has as rule that knight moves as knight, but captures as bishop, and vice versae.
* Some mini games are played on different sized boards.
* Some place pieces, that are not allowed to moved and / or captured.

What I am looking for is a library (preferred Javascript) that allows to add easily additional rules, and define for each game which rules are mandatory. Do you have recommendations about this?

# Answer
> 2 votes
Fairy-Stockfish supports configuration of chess variants at runtime, and it also has bindings for Python (pyffish) and Javascript (ffishjs) which can be used as libraries for chess variant game logic. E.g., PyChess has very few game logic built in, and uses both bindings in backend and frontend for the variant rules.

If you do not want to build something on your own, ChessCraft might be an alternative to be able to define and play variants directly in a UI.

---
Tags: programming
---


title: The King's ability to promote a piece

text:
# Question
Title: The King's ability to promote a piece
If the King makes it to the eighth rank and then back to the first rank, can he promote a piece like a pawn can when it reaches the eighth rank?

# Answer
> 6 votes
No. The whole point of the game, the way you win, is by checkmating the opponent's king. If your opponent could exchange the king for another piece then you would no longer be able to win.

In any case, all the pieces except the pawns can move backwards. Without promotion any pawn which reached the 8th rank and couldn't promote would no longer be able to move. That doesn't apply to all the other pieces.

FIDE, the international chess federation publishes the laws of chess on their website. The first 5 articles describe the rules for general play. The articles from 6 onwards describe additional rules which apply to official competitions.

---
Tags: rules, pawn-promotion, kings
---