# Question
Title: When (if ever) was it a rule that pawn promotion was optional?
I'm reading a very old chess book ("The Chess Pocket Manual" by G.H.D. Gossip, copyright 1894), and I find this passage in it's section on "The Laws of Chess":

> When a Pawn has reached the eighth square, the player has the option Of selecting a piece, whether such piece has been previously lost or not, whose name and powers it shall then assume, or of deciding that it shall remain a Pawn.

There is a footnote on this that reads:

> This is the famous " dummy " Pawn rule laid down in case of a position where a player, compelled to take a piece, would thereby lose the game, whereas, by refusing promotion to his Pawn, he could draw it. Need less to add that such positions, although possible, are extremely improbable, and do not occur in the course of a lifetime to most players.

When was this ever a rule? I've never heard of this.

If it was a widely recognized rule at some point, when did it change?

# Answer
**Dummy Pawns**

Today, it is little known that for forty years at the height of the British Empire, dummy pawns were the scourge of tournament play, and even grandmasters ran scared. (Possible exaggeration here.)

The heresy raged from 1862-1904. See *Eminent Victorian Chess Players: Ten Biographies* by Tim Harding. However, the origins of the dummy pawn goes back to at least 1832 and before.

**Timeline of known events**

(+/- indicate events pro/con the dummy pawn concept)

```
1832 + the earliest known reference to the dummy pawn is printed in “A new treatise of chess” by George Walker
1847 + the first known chess problem with the dummy pawn in it occurs in the American Chess Magazine
1851 + arrival in London, first appearing in the “The Chess Player’s Chronicle,” and called “The Revolutionary”
1854 - an example by Alexander Petroff appears in “Règles du jeu des échecs” in which the concept was denounced
1860 - Howard Staunton in his "Chess Praxis" wrote "no one will consider [dummy pawns] worthy of serious consideration."
1862 + International London Congress - provides an official rule for dummy pawns
1865 - William Pavitt, UK, explores the effects on chess composition in “The Chess World”. He describes it as "an exquisite stroke of chess legislation," but still condemns the concept.
1870 + Baden Congress - takes same line as London Congress of 1862.
1876 - new edition of Staunton's "Chess Praxis" - his rules still say no dummy pawns
1879 - American Chess Journal - "a frivolous and undesirable innovation"
1880 + Fred Thompson, in “Pawn on 8 In Chess Problems,” advocates for them as aids in chess composition
1883 - London International Chess Congress bans dummy pawns
1883 + Francis C. Collins composes a s#2 allumwandlung for “The New Zealand Mail”
1889 + Steinitz - supports London 1862 decision, and reports that so have many Congresses
1894 + "The Chess Pocket Manual" describes the "famous Dummy Pawn rule"
1895 - the legendary Hastings congress bans dummy Pawns
1898 + a spectacular Sam Loyd #3 composition
1900 + a superb #4 by E. J. de Savornin Lohman
1903 - there is an unsupported statement that the reign of dummy Pawns ended in this year ([http://www.chess-poster.com/english/history/the_pawn.htm][1])
1904 - founding of British Chess Federation, which according to Harding published the rules that finally exiled the monstrous dummy pawns to history
1913 + leading problemist Thomas R. Dawson composes a classic study with 3 dummy pawn promotions by White
1996 + John Beasley publishes a dummy pawn promotion study in EBUR
2017 + dummy pawns gains new life in chess.com and Matplus.net forums
2018 + chess.stackexchange.com diagram editor (still) supports dummy pawns
2020 + Popeye & Jacobi problem engines (still) support dummy pawns

```

See dummy pawns in action in our own heretical diagram editor below! (Except for the Ponziani game which is even more bonkers, and cannot therefore be animated correctly.)

**1832: A Concept Develops**

The origin of dummy pawns is mysterious and unknown. It most likely occurred in the early 19th century though. However, there is some sparse record of it. The earliest known reference to the dummy pawn is in 1832 from the book “A new treatise of chess” by George Walker.

On top of page 15, under the section “No. XX.,” pawn promotion is briefly described.

“When you have advanced the pawn to the extreme rank, or eighth square of the board, it immediately assumes the power of any piece you chuse \[sic\]. (The constitution of the game, would, of course, not allow of your demanding a second King, but you may have as many Queens, Knights, &c. as you can get. En passant, I may be allowed to add, that it is presumed from the wording of the law, **you might not call for a pawn, and replace it at its own square; but might certainly, for argument's sake, leave it as its eight square, *as a Pawn,* without exchanging it for an piece.)”**

The text we have put in bold does not say “dummy pawn” exactly, but the language is clear enough. Dummy pawn is the central subject.

**1847: A Misty Appearance In America**

The first known chess problem that uses the dummy pawn is from “The American Chess Magazine” in the year 1847. On page 113 the following problem was shown with the attached question.

```
[Title "F. Leake - American Chess Magazine 1847, Can White force checkmate in five moves? "]
[FEN "2B5/8/1K1k4/4pP1N/3pP3/Pp1P4/p7/7R w - - 0 1"]

```

It says: “ A question of great importance - one which is not provided for in the laws of the game of Chess, and to decide which we know of no precedent- is here involved. Can White force Checkmate in five moves? That's the question."

If Black is obligated to promote to a piece, then there is a mate in 5: 1. f6! b2 2. Rb1 a1=B 3. Rxb2 Bxb2 4. Ng3/g7 ~ 5. Nf5/e8#. However, if Black may keep it as a pawn, then there is no mate in 5. There is a unique mate in 6 though: 1. f6! b2 2. Rb1 a1=Pawn 3. Kb7 Kc5 4. f7 Kb5 5. f8=Q Ka5,Ka4 6. Qb4#

On pages 136-139 appears correspondence giving opinions as to whether or not there is a mate in 5.

No: “(Skipped text) I presume that the question you raise is this: When a Pawn reaches the eighth square, is the player obliged to change it at once for a Piece, or has he the option of allowing it to remain dead on the eighth square? In my opinion, he is obliged to change it at once for a Piece ; he has no option but in the choice of the Piece so exchanged. The Twenty-third Law of Chess, according to Walker's Treatise, (1842,) is :— Directly the Pawn attains the eighth square, or extreme rank of the board, it must be replaced by a Queen, Rook, Knight, or Bishop, at the option of its owner; and this without regard to whatsoever Pieces he may already have on the board. Should you not replace the Pawn with a Piece, before your opponent move, he may take it off the board as forfeited. (Skipped text). Though you appear to think this a very nice question, I have but little doubt as to the nature of your decision, should you think proper to make one. And with all due deference to your well-earned reputation as a Chess-lawyer, I will venture to risk the opinion, that the " big wigs" in London will be surprised that you should regard the question as one unprovided for in the laws of Chess." - Philo-Chess

Yes: “(Skipped text) For myself, however, I incline to a different opinion. The Checkmate in this case cannot be forced in five moves, unless the Pawn, on reaching the "royal line," loses its character as a Pawn, and immediately and necessarily becomes a Piece of some kind; or unless Black is compelled, by some law of the game, to replace the Pawn at once by some Piece. (Skipped text) It is obvious that the right of promotion is granted as a favor or privilege, and that upon the assumption that a Piece is of greater value than a Pawn. Why, then, limit this privilege, by confining the choice to a Piece? Why, especially, require the player, who is entitled to a reward for his skill and success in conducting his Pawn to the "royal line," to submit to a positive disadvantage, by compelling him to exchange it for a Piece of inferior value to him? Finally and conclusively, the rule, strictly construed, is anti-republican-and this is a "free country!" Why should the Pawn have "greatness thrust upon him If he is satisfied with untitled merit, why not permit him to indulge his tastes for private station? Why elevate him, against his inclination, to a rank to which he does not aspire?“ - A.D.P.

The wonder is that this problem is much more sophisticated than any other dummy pawn problem that would be made for nearly two decades, until Pavitt came along with his 5-mover in 1865.

**1851: A Boost In London**

The dummy pawn, 4 years later, once more made an appearance on the other side of the Atlantic Ocean in Edward Winter managed to find the first mention of a dummy pawn endgame study in England in C.N. 7619. In the September 20, 1851 edition of “The Chess Players Chronicles,” the following problem called “The Revolutionary” appeared. This is where the dummy pawn truly started its reign.

```
[Title "Josef Kling & Bernhard Horwitz - The Chess Player 1851, Revolutionary Question XIX: How can White draw?"]
[FEN "r7/1Pp5/2P3p1/8/6pb/4p1kB/4P1p1/6K1 w - - 0 1"]

```

The solution, which was given in a week later, stated: “The solution of No. 19 is Pawn takes Rook, remaining a pawn. It may seem ridiculous to many chess-players, but we think candidly that, when first the rules were laid down, nobody thought of such a case, or else the rules would be a little more precise on that point."

In the correspondence section of the 9/20 issue the editors also said “ We are of opinion that a pawn, when reaching his eighth’s square, is entitled to become any piece the player thinks best; and, naturally enough, if it prove disadvantageous to become a piece, it may still remain a pawn. (See Diagram 19.) This question among others, we thought, should have been discussed at the Tournament.”

**1854: Spread In Europe & Rejection**

From 1851 onward, the idea of the dummy pawn seems to spread across Europe. One indication is the appearance of another dummy pawn problem, this one also being White to play and draw, that was created by the Russian composer Alexander Petroff and published in the 1854 French book Règles du jeu des échecs. On page 97, the problem was given.

```
[Title "Alexander Petroff - Règles du jeu des échecs 1854, White to play and draw"]
[FEN "rn6/pp2n3/2p5/P4k2/8/6p1/6Pp/7K w - - 0 1"]

1. a6 Nd5 2. axb7 Nf6 3. bxa8 null

```

However, this problem is **flawed** because Black can play 2... Nf4!, 3. bxa8 Nxg2 4. Kxg2 Kg4, and Black wins. White doesn't win even if they promote-3. bxa8=Q Nd3 4. Qxa7 Nf2+ 5. Qxf2 gxf2 6. g4+ Kxg4 winning.

The French text, roughly translates, reads: “This subject, we must say that Mr. Petroff communicated to us the following problem, in which, supposing the best possible blows on the part of the blacks, the whites could not postpone the game, unless they were allowed to refuse any promotion to their pawn entered lady, that is to say to leave it pawn. (Diagram of the problem.) On this occasion, Mr. Petroff asks us to submit to the judgment of the European authorities in matters of gambling, if it would not be advisable to introduce into the regulations a clause which would allow the possessor of a pawn entered to queen, to renounce to any increase in its forces, leaving this pawn inactive and immobile, as a pawn, until it is taken or until the end of the game?

(Skipped Text)

“For its part, the Society of Saint Petersburg Chess Lovers did not believe that it could accept this opinion (expressed in the form of doubt by Mr. Petroff himself), contrary to the fundamental principle of the game, which 'does not admit the existence of pawns to the strips of the chessboard originally occupied by the pieces.'"

This shows that the dummy spread like wild fire, relatively speaking for the times, and within 3 years it was already an outrage in at least France and Russia. It would take awhile for the English to get their turn.

**1860: Staunton, bastion of orthodoxy**

The "dummy pawn rule" was not part of the official rules up to 1860. See "Chess Praxis" by Howard Staunton 1860. Staunton was a very influential player and author, and in this book codified the Laws of Chess, in a way which is still recognizable in the style of the FIDE Laws today. On page xi, in the Introduction he lists chronologically the many antecedents of his work from Ruy Lopez in 1561, to the 1850s.

**Page 6, Queening a Pawn:* “When a Pawn has reached the eighth or last square on its file, it immediately assumes the name and power of any Piece its player may select, except a King, whether such Piece have previously been lost or not; and, if the player does not select a Piece, such Pawn is always to be considered a Queen.”

On page xii, he had defined "Piece" to explicitly exclude pawn. The real fun comes later:

**Chapter 4, "A Queened Pawn:** “On this subject great difference of *opinion* prevails, but the rule laid down in the text is that universally observed in practice. In the middle ages, as we have previously explained, the Queen could only move one square at a time diagonally. She was, therefore, by far the weakest piece on the Board. And the ancient law, which required that every Pawn pushed on to the eighth square should become a Queen, was really a restrictive enactment, since it gave the promoted Pawn as little additional power as the conversion could offer. But the spirit of the modern game is to regard the Queening of a Pawn as the highest feat a player can accomplish, and to reward it with the greatest possible advantage. So that a player in the present day is not only allowed to select a second or third Queen with its enormously extended power, but may choose any other Piece that would be more advantageous in a particular position. Various modifications of this law have existed in different places and at different times. It has been held, for example, that the Pawn should only acquire the power of the Piece on to whose square it had been played, or of a Piece already lost. It has also been proposed to limit the conversion to either a Knight or a Queen, as the latter comprises the power of Rook and Bishop; and the Pawn has sometimes been required to perform certain additional moves before becoming entitled to the privileges of a Piece. The most plausible of the regulations is that the Pawn should only supply the place of a Piece already lost, so as to avoid, what Philidor so violently denounced, plurality of pieces. But then comes the difficulty of providing for the case where a Pawn has reached the eighth square before any Piece has been lost. It has been proposed to leave such a Pawn, as it were, dormant, until a capture should have made among the Pieces a vacancy for it to supply. Ponziani, an advocate of this regulation, has given the following little game as an example of it.”

Example of non-standard castling & promotion

```
 [Title "Ponziani scheme - White to move"]
 [FEN "Bn1qk1nr/p1p2ppp/8/8/4P2b/5N1b/PPPP3P/RNBQ1rK1 w k - 0 1"]

```

*1. e4 e5 2. f4 exf4 3. Nf3 Be7 4. Bc4 Bh4+ 5. g3 fxg3* 6. Kh1&Rf1 d5 *Italian style castling!* 7. Bxd5 Bh3 8. Bxb7 g2+ 9. Kg1 gxf1 *without promoting* 10. Bxa8 Bf2# & f1=R# *only now does pawn f1 promote to a rook*

“In this game the black Pawn, which attained the eighth square on its ninth move, neither gave mate nor check, because the player had lost no Piece into which it could be converted, and it was not in a situation to check as a Pawn. But as White chose to capture the Rook on his tenth move, Black plays down the Bishop with one check, giving another and mate, with the Pawn now become a Rook in place of that captured. There is so much of the absurd about such a finale as this that no one will consider it worthy of serious examination, and it is only mentioned as a matter of curiosity.”

**1862: The Madness Becomes Official**

As described in the Edward Winter link in another answer, the dummy pawn rule was codified in the International Congress of London in 1862, despite Staunton's outrage. For a generation, the war raged between the two camps, echoing the chaos in the European political space at this time. English chess papers would bicker about it for decades to come, with numerous joke problems and articles, with most condemning the dummy pawn.

**1865: Some Chess Composers Grumble**

In 1865, 3 years after the passing of the law allowing the dummy pawn, an early article by William Pavitt against the dummy pawn appeared in the “The Chess World”.

Pavitt gave this simple mate in three he created that worked under normal promotion rules

```
[Title "William Pavitt - The Chess World 1865, Mate in 3"]
[FEN "K7/2N5/2p5/k1P3R1/p4N2/P2P4/6p1/8 w - - 0 1"]

1. Ng6! g1=Q 2. Ne5 Qc1 3. Nxc6#

```

However, in essence, with the dummy promotion rule, the problem wouldn’t work as there is no mate in two. He showed  mate in 5 to show how the problem would have to be corrected to conform with the dummy pawn. (Note that this is a correction the original created by James Malcom as the original is incorrect).

```
[Title "William Pavitt (corrected J. Malcom 2020), Mate in 5"]
[FEN "8/K1N5/2p5/k1P5/p7/P2PP3/3p2pN/3B4 w - - 0 1"]

1. Ng4 g1 2. Bf3 d1 3. Bd5 cxd5 4. Ne5 d4 5. Nc4#

```

Pavitt showed these problems to give examples on how allowing the dummy pawn would greatly affect chess problems, and he condemned the concept as negative.

Most chess composers in the chess problem world were eventually set against the dummy pawn due to how it would interfere with known chess problem and the needless work that would be needed to incorporate it in. An occasional exception, i.e. Christmas and trick problems that intentionally used it, was generally accepted for the humor. In fact, many problem tournaments specified to rules to disallow the dummy pawn.

**1870: Baden**

A typical data point from this dark time is the Baden Chess Congress of 1870, which adopted the 1862 rules (\[source\]\[2\]). An article covering this begins attractively:

“Unmoved by the shrill notes of the war trumpets sounding in their ears, the Chess players have commenced their mimic strife in Baden.“

**1876: Staunton**

In the mean time, Staunton came out with another edition of his Praxis (\[source\]\[3\]). He did not mention the 1862 rules, but he did give the previously discussed 1854 example by Petroff.

**1880: A Rare Friend To The Dummy**

However, not everyone gave disdain to the dummy problem. A few chess composers thought that it should be allowed. An old article by Fredrick Thompson, published in 1880 in “Chess Player's Annual And Club Directory,” called on “Pawn On 8 In Chess Problems” gives an insight into the supporters of the dummy pawn. In his article. Thompson advocated for the dummy pawn to be allowed in chess problems.

Various reasons are given, the most interesting perhaps being this: “ The main objection to P on 8 is, that it breaks a fundamental law of Chess. So it would if pawn stood on square 1, but on square 8, in the enemy's territory, is quite another thing. As Staunton in his Praxis says—" The ancient idea supposed the Chess Board divided into two belligerent kingdoms." Have common soldiers never mounted guard in the palace of a foreign potentate at the conqueror's behest? Ought pawn to be played to 8 at all if he may not remain there? His captain bids him stand sentinel as a private soldier, and it is not for the discomfited foe to say him nay. Ought pawn to attack a piece or check the King from square 7, if he has no business on 8?”

The logic is that if the pawn has power on the 7th rank as a pawn, why should can it not extend its rights as a pawn on the 8th rank?

A more straightforward reason is also given: “The present pawn-queening law bristles with innovations upon ancient usage. As Mr. Staunton wrote on March 18, 1865—"The old laws from which you quote, have been constantly modified of late years." Fundamental law, forsooth! The law never had a bottom. No one will deny the use of pawn on 8 in problems if pawn on 8 is permissible in play. The " Competent authority " for the laws of Chess must be players, not problem composers, for the laws, of the game govern the problemist, not the problemist the laws of the game.”

Lastly, he advocates for it as to prevent cooks in chess problem, to make possible otherwise impossible ideas realizable at last. He gives a problem to illustrate his defense of the dummy pawn, since it would be cooked without the pawn on c8, since without there would be a cook starting with 1. Qc8+.

```
[Title "Fredrick Thompson, Mate in 3"]
[FEN "2PQ4/6p1/3P2B1/3Pk3/8/2N1N1P1/8/7K w - - 0 1"]

```

He ends with this: “ I claim, therefore, P on 8 in Chess strategy, and conclude this paper with a problem commenced in July, 1879. (Skipped text). Dropping the men one square down the board also produces a cook, in fact the dead pawn saves the problem from being relegated to the waste basket. I consider this one of the best compositions I have put together during a practice of thirty years, and I fail to see why it should be treated to Lynch-law, when the queening-a-pawn rule is to "reward it with the greatest possible advantage."

**1883: London Congress**

Another data point is the London International Congress of 1883, where the rules include:

“10. A Pawn reaching the eighth square must be named as a Queen or Piece, at the option of player, independent of the number of Pieces on the board. The created Queen or Piece acts immediately in its new capacity. Until the Pawn has been so named, the move is incomplete.”

This is the first occurrence I've ever seen a usage of Piece to exclude the Queen! However, it's clear that dummy pawns are on the wane.

**1883: Far Reaches-The Dummy Pawn’s Travels**

One example that can be found of how far the dummy pawn reached is a problem from the 3/10/1883 edition of the “New Zealand Mail.” New Zealand was then part of the British Empire, is so not so surprising that the dummy pawn got that far, but it is pretty far though!

```
[Title "Francis C. Collins - New Zealand Mail 3/10/1883, Selfmate in 2"]
[FEN "1n3R1n/3p1p2/B1pP1Pp1/2B1K1P1/2r5/3k4/NR2p1Q1/8 w - - 0 1"]

```

The point is that capturing the b8 knight fails because Black can then promote to a pawn and there is no selfmate after that. The solution is 1. Rxf7!, such that after e1=P, the move. 2. Rxb8 forces 2... Nxf7#.

The solution, printed in the 4/21/1883 edition, says this: "This position has been composed by Mr. Collins in accordance with the British Chess Association’s 13th Law: —“When a pawn has reached the eighth square, the player has the option of selecting a piece, whether such piece has been previously lost or not, whose name and powers it shall then assume, or of deciding that it shall remain a Pawn.” This rule of the “dummy pawn” has never met with much favour amongst chess-players, and there are very few clubs or societies which observe it. We have received no correct solution to the problem (which is a most ingenious one), the result doubtless of the non-acquaintance by our friends of such a rule as the foregoing in any of the codes of chess laws."

This shows just how weak of an entity the dummy pawn has become and how very few looked upon it with favor.

**1895: Hastings Congress**

By the time of the famous Hastings Congress in 1895, dummy pawns are clearly gone from serious play. The Congress rules adopt exactly the same wording as London 1883. (All attendees were searched to make sure no dummy pawns were being smuggled into the venue.)

**1898: Sam Loyd #3**

In what is widely known as the last hurrah, no discussion of the dummy pawn period would be complete without the following beautiful problem by the American composer Sam Loyd.

```
[Title "Sam Loyd - American Chess Magazine, Mate in 3"]
[FEN "N1Br4/2Pb1P2/3k4/1P2R3/1P2K3/B7/8/8 w - - 0 1"]

1. cxd8!
(1. cxd8=Q/R? stalemate)
(1. cxd8=B? Bf5+)
(1. cxd8=N? Bc6+)
threatening 2. f8=Q/B#
(1... Bf5+ 2. Rxf5 Ke7 3. f8=Q#)
(1... Bc6+ 2. bxc6 Kxc6 3. b5#)
(1... Bxc8 2. f8=Q+ Kd7 3. Qe7#)
(1... Bxb5? 2. Re6#)

```

**1900: An Ingenious #4**

But in fact Loyd's was only the penultimate hurrah. Two years later the brilliant but little-known E. J. Lohman produced this gem, which is as ingenious as Loyd’s #3. This is what should be known as the last hurrah of the dummy pawn, the pinnacle of the times when you could make a position and legally solve it by promotion to a dummy pawn.

```
[Title "E. J. de Savornin Lohman - De Amsterdammer 02/09/1900, Mate in 4"]
[FEN "2B5/1pR1P3/1P1k4/8/2K5/5P2/8/8 w - - 0 1"]

1. e8! Ke5 2. Rf7 Kd6 3. f4 Kc6 4. Rf6#
(1. e8=Q/R? stalemate!)
(1. e8=N+? Ke5 2. Rf7 stalemate!)
(1. e8=B? Ke5 2. Rf7 Kd6 3. f4 stalemate!)

```

**1904: The Mischief Ends**

But it was only with the arrival of the British Chess Federation that the final nail in the coffin was driven home. There is still some lack of clarity as to the precise year this happened, but it was around 1904.

**1913: ...And Yet**

Nearly a decade after the dummy pawn was finally killed off in law, the famous fairy chess composer Thomas R. Dawson took some time to make a drawing study with it. White must create three dummy pawns in order the achieve the draw via self-stalemate!

```
[Title "Thomas R. Dawson - The Chess Amateur 1913, White to move and draw"]
[FEN "6K1/6PP/3p2PP/3P1ppp/8/ppp5/qrp5/1rk5 w - - 0 1"]

1. Kh8 Kd2 2. g8 Re1 3. g7 Re6 4. dxe6 Rb1 5. e7 b2 6. e8 Qxg8+ 7. hxg8 null 8. h7 null

```

Afterward, the dummy pawn slowly faded into history, only mentioned now and then, until the dawn of the Internet.

**1996: A Lone Bright Spot**

In 1996, the dummy pawn had another brief period of relevance when John Beasley made a small study in which the only way for White to win is to promote to a pawn. It is the first known dummy problem in which White wins since the Loyd #3-nearly a century! I will leave to you figure out the reasons to avoid promoting.

```
[Title "John Beasley - EBUR 1996, White to move and win"]
[FEN "5r1K/2k1P3/3N1Bqp/N2Q1B1P/8/8/8/1R6 w - - 0 1"]

```

**2017: Just For Fun**

The Internet has allowed many to create and share their own dummy pawn problems. While there is no doubt many problems been created, perhaps the pinnacle of achievement was when Peter Wong created an entirely new problem in which White wins by promotion to a pawn!

The problem was shared on the Matplus.net forums in November, 2017, although. the composer has originally shared somewhere on chess.com.

The chess composer Geir Sune Tallaksen Østmoe managed to add a golden touch to Peter Wong in that it is in both sides best interest to promote to a pawn!

```
[Title "Geir Sune Tallaksen Østmoe & Peter Wong - Matplus 11/12/17, Black to move and White to win"]
[FEN "5qnk/3pPB2/1p1p1N2/1pbK1NP1/1p1pP3/1P1P4/6p1/7R b - - 0 1"]
[startflipped ""]

1. gxh1! exf8!

```

White easily wins with an extra piece. The full solution and the refutations of each promotion can be viewed here.

Also from the same forum, here are two possible 6-piece settings for dummy pawn draw:

```
[Title "ichai - MatPlus 7/2/2020, White to move and draw"]
[FEN "8/2P5/8/8/8/2r5/p1r5/K1k5 w - - 0 1"]

1. c8!
(1. c8=Q? Rb3)

```

And the current economy record-holder:

```
[Title "A.Buchanan - MatPlus 13/5/2020, White to move and draw"]
[FEN "7K/5rPp/7k/8/8/8/6p1/8 w - - 0 1"]

1. g8!
(1. g8=Q? g1=Q! 2. Qxg1 Rf8+ 3. Qg8 Rxg8+ 4. Kxg8 Kg6!
    (2. Qxf7 Qd4+ 3. Kg8 Qd8+ 4. Qf8+ Qxf8+)
    (2. Qf8+ Rxf8#)
    (2. Qg7+ Qxg7#)
    (2. Qxh7+ Rxh7#)
    (2. Qg5+ Kxg5)
    (2. Qg6+ Kxg6,hxg6))

```

**Will the dummy pawn rise again?**

It seems unlikely that FIDE will introduce the dummy pawn for over the board play, although it would be cool if they did. For compositions, dummy pawn promotion, as the ultimate under-promotion, is paradoxical and dramatic: exactly what a problem chess move should be. However, introducing a 5th promotion option would render incomplete the vast range of allumwandlung studies, including solutions to the famous Babson task. So this novelty seems unlikely to happen.

**Where Can I Find Dummy Pawn Problems?**

Currently, the largest known catalogue of dummy pawn problems is on the Die Schwalbe Chess Problem Database Server, known as the "Schwalbe PDB for short. Searching "K='dummy pawn' in the search function currently brings up a list of 63 dummy pawn problems, from across the 19th-21st centuries. It is but a small sample of what exists out there.

*Extensive edits and additions were carried out by Rewan Demontay May 6, 2020.* *Some follow-up mods by Laska subsequently: let's keep building it!* *Addendum 8/31/2020-The history of the dummy pawn has been pushed back to 1832.*
> 69 votes

# Answer
Edward Winter cites Owen J. Clarkin (Ottawa, Canada) who quotes from The Modern Chess Instructor by W. Steinitz (New York, 1889) which in turn cites this example from Lowenthal's *Book of the London Chess Congress, 1862*:

```
[Title "Dummy pawn motivation"]
[fen "r/1Pp5/2P3p1/8/6pb/4p1kB/4P1p1/6K1 w - - 0 1"]
[StartFlipped "0"]

1.bxa8=Q gxh3

```

If White plays 1. bxa8 and promotes to a piece, then Black plays 1 ... gxh3 and it is mate next move. But if White plays 1. bxa8 with no promotion, then either White gets stalemated, or a drawn endgame is reached with White's white-squared bishop versus Black's black-squared bishop.
> 37 votes

---
Tags: rules, history, pawn-promotion
---


# Question
Title: Availability of AlphaZero and A. Grischuk's idea in the Anti-Moscow Gambit vs L. Ding
I was watching some Fide Candidates post play conference and Grischuk mentioned that a certain move was suggested by `AlphaZero`. So I was googling a little and have a stupid question. Where is `AlphaZero`? I thought it is non-public and no-access engine and I really cannot find anything but an implementation of the algorithm on `github` based on their published paper but from the page it seems it is not really the `AlphaZero`.

So does anyone have more insight if `AlphaZero` engine is somewhere available to use or even play against? How would Alexander Grischuk have access to it?

# Answer
No, as far as I know DeepMind's AlphaZero chess program has not been publicly released in any form, and I don't know if they plan to do so at any point. The only games of AlphaZero vs Stockfish that have been publicly showcased are the 10 games that can be found either in their pre-print paper, on their website or the chess news outlets such as chess24.

I guess the comment you're referring to is the one made during the press conference by Alexander Grischuk after his first game vs Liren Ding, where they played the Anti-Moscow variation of the semi-Slav Defense, an opening that has **not** occurred in any of the published sample games of AlphaZero vs Stockfish. So for all we know, as ETD has also pointed out in comments, Grishuk is *jokingly* labeling probably his `16.a4` novelty (or possibly the whole sacrificial variation after `Nxf7`) as an idea liked by AlphaZero but disliked by Stockfish. This is also pointed out in the chess24 report of the 4th round.

Grischuk essayed `16.a4` in this variation where the main move is usually `16.Bg4` (which became famous after the Topalov vs Kramnik game in 2008):

```
 [title "Semi-Slav Defense: Anti-Moscow variation 16.a4"]
 [fen ""]
 [StartPly "38"]

 1. d4 Nf6 2. c4 e6 3. Nf3 d5 4. Nc3 c6 5. Bg5 h6 6. Bh4 dxc4 7. e4 g5 8. Bg3 b5 9. Be2 Bb7 10. O-O Nbd7 11. Ne5 Bg7 12. Nxf7 Kxf7 13. e5 Nd5 14. Ne4 Qb6 15. Nd6+ Ke7 16. a4 (16. Bg4)

```
> 6 votes

---
Tags: opening, alphazero, novelties
---


# Question
Title: Would a player or computer with infinite proccessing time be unbeatable?
Forgive me if the answer is obvious, but I wondered about this for a while. In a game where one player can calculate all possible moves (whether the amount is more or less than atoms in universe or whatever) and another does not, would the first one always win? In a game where both players can do that, would first-mover always win, or will the games always conclude in draw? To calculate, 'see', all possible game progressions from the moments the game field is set, before the game even begins, does that mean what the game is beaten? This seems like a logical conclusion, is it?

# Answer
No, a player who can calculate for infinite time can play a perfect game of chess, but this does not automatically mean that he always wins.

From the game theory perspective, we know that chess is a finite game, so it admits a perfect strategy. Anyway we don't know what is the result of that perfect strategy. There are three possibilities: the perfect strategy could be a win for White, or it could be a draw, or it is also possible that the perfect strategy would lead to a win for Black. (This last possibility is very unlikely, and nobody believes in it, but I think it has theoretically not been ruled out. It would be amazing if the perfect strategy were a win for Black, it would mean that the initial position of chess is just a big Zugzwang!)

If the perfect strategy from both players leads to a draw, then it means that your perfect players does not necessarily win every game. Some imperfect but good opponent could manage to draw some times.

On the other hand, if the perfect strategy leads to a win for White, then your perfect player would always win with White, but as soon as he plays Black, he has a chance to draw some times against an imperfect but good opponent, and he could also lose sometimes.
> 5 votes

---
Tags: calculation
---


# Question
Title: What ELO is it good to learn and play the Kings Indian Defense OTB?
I am roughly 1400 USCF and when I play against 1. d4, I tend to avoid the theoretical stuff (Benoni, KID) and defenses such as the Nimzo and QID (mostly anything hypermodern). So I stick with the classical 1... d5 defenses mostly. But, as I am becoming a better chess player I am looking towards other openings; I have played the KID over some casual games and of all of the other d4 defenses, I play the KID intuitively pretty well.

However, what is making me reluctant of it is defending against the Four pawns attack, Saemisch, and Averbakh lines (or anything where white plays a early Bg5) are a bit annoying. But I enjoy playing against the classical lines.

What would be a good choice?

# Answer
Elo points don't matter. Just play what opening you feel comfortable with most. If you play it well intuitively, then go ahead.
> 8 votes

# Answer
You can adopt it in OTB play at any time. The Kings Indian Defense is a very solid one, but like all openings it will take time and practice to familiarize yourself with many of the lines. I would suggest continuing to play in informal games to build up your exposure. If a position comes up that confuses you early on, take note of the board position and spend some time with it later reviewing it with an engine or against master-play databases to see common lines.

The theory of the opening is very different from what you've been playing. If you haven't yet, I'd suggest looking into that aspect as early as possible and watch how it comes alive in players who have favored the opening like Fischer.
> 2 votes

---
Tags: kings-indian
---


# Question
Title: Output whether the best move is "much better" or only "slightly better" than the other moves
On Oct 31, 2014, Tord Romstad wrote:

> The moves are not searched in descending order from best to worst. Stockfish has no idea which move is the second, third best, etc., and it doesn't have any centipawn scores for any moves other than the current best move. For the rest of the moves, the centipawn scores are unknown, all we have for those moves are upper bounds for the centipawn scores.
>
> As an example, assume that we have a position with four legal moves A, B, C and D. What Stockfish knows about the centipawn values of the four moves after searching to a given depth would usually be something like this:
>
> Move A (best move): 100 centipawns.
> Move B: At most 50 centipawns
> Move C: At most 80 centipawns
> Move D: At most 0 centipawns
>
> Because we only have upper bounds for moves B, C and D, we have no idea which of these three moves is the best.

Is there a way to make Stockfish output the data described by Tord? I would argue that it is valuable to not only know the best move, but also to have an idea of whether the best move is "much better" than the other moves or only "slightly better".

# Answer
I don't think Stockfish gives you the information as it's not useful to anybody other than programmers for debugging. The best way is just run MultiPV=2, and subtract the best two moves. Is there any reason why you can't do that?

If you insist you'll have to modify the source code yourself. It's not a very hard change. But why would you do that?
> 2 votes

---
Tags: engines, software, stockfish, programming
---


# Question
Title: How to make Lichess local analysis utilize more cpu and memory?
I get around x12 faster evaluation when I run Stockfish myself, so I checked my utilization when running local analysis (Chromium and Firefox) and saw that it just utilizes one thread and few megabytes of memory.

So I am looking for a solution to make it fully utilize my hardware. Any ideas?

---

## EDIT:

**TL;DR** Issue was user-agent specific, doesn't work on Chromium/Ubuntu.

# Answer
> 3 votes
The menu for the analysis board has sliders for CPUs and memory (see screenshot below). Have you tried adjusting those? Maybe whether they actually work or not depends on which browser you are using. If they don't, I think this question would be best suited for the Lichess feedback forum, since it might be a bug.

---
Tags: engines, performance, lichess
---


# Question
Title: alpha-beta algorithm returns a value between alpha and beta inclusive?
I am coding up a chess engine and using the alpha-beta algorithm for tree scanning. I ended up doing what they posted here:

```
int alphabeta(int depth, int alpha, int beta)
{
    move bestmove;
    if (game over or depth <= 0) return winning score or eval();
    for (each possible move m) {
        make move m;
        score = -alphabeta(depth - 1, -beta, -alpha)
        if (score >= alpha) { alpha = score; bestmove = m; }
        unmake move m;
        if (alpha >= beta) break;
    }
    return alpha;
}

```

It is stated that "The code above always returns alpha, beta, or a number between alpha and beta." In my calcs this is not true and I need it in order to implement aspiration search. I have seen many variants of the algorithm and tried a few but sometimes the return value falls outside the desired interval \[alpha, beta\].

1. Can anyone post C++ or pseudo-code of alpha-beta with that property?
2. Is it possible to prove that ?
3. Finally, it seems intuitive that the return value is an increasing function of alpha keeping beta fixed and similarly for beta. Is it true and is it provable? In my calcs this is not the case.
4. How big must be the window of aspiration search in order to ensure we have not pruned out the principal variation? If the return value falls between alpha and beta will that suffice?

# Answer
> 2 votes
My usual reference is https://chessprogramming.wikispaces.com/Alpha-Beta#Implementation-Negamax%20Framework, which I believe is correct.

In your lecture slide, if `score > beta` ==\> `alpha = score` ==\> return alpha which is greater than beta. Thus, the claim looks incorrect to me.

You don't need to prove "*increasing function of alpha*" because any score less than alpha is a bad move for you, so you would ignore it.

Aspiration window width is a parameter and there is no definitive answer. You don't want it too big, or too small. You'll need to run tests...

---
Tags: opening, engines, software, strategy
---


title: Forcing a draw with knight and king

text:
# Question
Title: Forcing a draw with knight and king
Can white force a draw somehow from this position using only his knight and king?

# Answer
No. Even assuming it's White's move, Black can force mate in five moves according to the computer. But you don't really need to calculate that much since Black's material advantage is so overwhelming.

The only hope would be a stalemate, but it is unlikely. To achieve that, the knight would have to be pinned or lost, but I don't see how you can force that: if it got pinned, Black could just unpin it in the next move if necessary, or simply capture it. Even trading the queen for the knight, the position would still be easily won by Black. Black only needs to make sure that if they take the knight, they don't cause an immediate stalemate (that would be Black's blunder, not something forced by White).

Here's one of the possible lines that end with mate in five:

```
8/p7/6k1/2p5/6r1/2N4q/1K6/8 w - - 0 1

1. Kc2 Rc4
2. Kd1 Qd3+
3. Ke1 Rxc3
4. Kf2 Rc2+
5. Ke1 Qe2#

```
> 7 votes

# Answer
It is not possible to force a draw. Even if Black somehow lost both pawns and his rook, the resulting endgame is still won for Black.

```
[FEN "8/8/6k1/8/8/2N4q/1K6/8 w - - 0 1"]

1. Kc2 Qg4 2. Nb1 Qd4 3. Nc3 Kf5 4. Ne2 Qe3 5. Nc3 Ke5 6. Kb2 Qd3 7. Na4 Qb5+ 8. Ka3 Kd4 9. Nb2 Ke3 10. Nc4+ Qxc4 11. Kb2 Qb4+ 12. Ka2 Kd3 13. Ka1 Kc3 14. Ka2 Qb2#

```
> 4 votes

# Answer
Black has Rg2, Qh1. The only way that's not checkmate is if white interposes the knight, but then the knight is pinned and can be taken.
> 0 votes

---
Tags: learning, endgame
---


# Question
Title: A new AI wins at go. Can a similar AI win at chess? Can it achieve pure self-training?
One of the more popular questions asked on this site regards the prospect of a purely self-trained chess AI.

Today, ChessBase is distracted from its coverage of the FIDE Candidates tournament to report that a new AI is, for the first time, beating a leading master of the rather different game of go, which had resisted chess-style AIs for many years. An initial reading of the report suggests that the new go AI is unlike chess AIs, but is more nearly a general-game-playing (GGP) AI. ChessBase's article does not however use the term GGP, but does seem to say that *the go AI can win at simple video games.*

Is there any reason such a winning go AI could not with minor adjustments also win at chess? If so, does such an AI show promise to achieve the pure self-training the several excellent answers to the earlier question have earlier discussed, which at that time was not yet possible? Why or why not?

I suspect that no really complete, fully informed answer to my question is yet available, so even a partial answer based on related expertise would be appreciated.

For additional reference, see also this related question and answers.

**UPDATE**

When the above question was first posted five days ago and when some of the fine answers below were given, the first news regarding the victory of the go AI had just appeared. Since then, additional information and commentary have emerged.

Particularly interesting since then has been a quite readable, five-sided roundtable discussion in which one Jonathan Schaeffer remarks:

> Learning from human games helps accelerate the program’s learning. AlphaGo could learn to become a strong player on its own, without using the human games. The learning process would just take longer.

According to the roundtable's host, Schaeffer is "\[c\]omputer science professor at the University of Alberta and the man who solved checkers"; so, presumably, he might be qualified to comment.

For further information, here is the record of another, open discussion, many of whose participants seem better informed than usual. The discussion took place during the match.

*Further update, a year and a half later:* commenter @MarkS. writes:

> This is just a comment because it's about Go, not Chess, but AlphaGo Zero achieved "pure self-training" just from being told who won (and not the final score) and is stronger and vastly more efficient than the AI that beat Lee Sedol. For more information, see deepmind.com/blog/alphago-zero-learning-scratch

# Answer
Well, well, well! DeepMind have published a paper in which they say they have programmed and trained a neural network computer to beat Stockfish.

With 1 minute thinking time per move their AlphaZero computer beat Stockfish by +25, =25, -0 with white and +3,=47,0- as black.

They "trained" 3 separate computers to play chess, shogi and Go and beat their silicon rivals convincingly.

Here is how the paper describes the training and evaluation -

> Self-play games are generated by using the latest parameters for this neural network, omitting the evaluation step and the selection of best player.
>
> AlphaGo Zero tuned the hyper-parameter of its search by Bayesian optimisation. In AlphaZero we reuse the same hyper-parameters for all games without game-specific tuning. The sole exception is the noise that is added to the prior policy to ensure exploration; this is scaled in proportion to the typical number of legal moves for that game type.
>
> Like AlphaGo Zero, the board state is encoded by spatial planes based only on the basic rules for each game. The actions are encoded by either spatial planes or a flat vector, again based only on the basic rules for each game (see Methods).
>
> We applied the AlphaZero algorithm to chess, shogi, and also Go. Unless otherwise specified, the same algorithm settings, network architecture, and hyper-parameters were used for all three games. We trained a separate instance of AlphaZero for each game. Training proceeded for 700,000 steps (mini-batches of size 4,096) starting from randomly initialised parameters, using 5,000 first-generation TPUs to generate self-play games and 64 second-generation TPUs to train the neural networks. Further details of the training procedure are provided in the Methods.
>
> Figure 1 shows the performance of AlphaZero during self-play reinforcement learning, as a function of training steps, on an Elo scale (10). In chess, AlphaZero outperformed Stockfish after just 4 hours (300k steps); in shogi, AlphaZero outperformed Elmo after less than 2 hours (110k steps); and in Go, AlphaZero outperformed AlphaGo Lee (29) after 8 hours (165k steps).
>
> We evaluated the fully trained instances of AlphaZero against Stockfish, Elmo and the previous version of AlphaGo Zero (trained for 3 days) in chess, shogi and Go respectively, playing 100 game matches at tournament time controls of one minute per move. AlphaZero and the previous AlphaGo Zero used a single machine with 4 TPUs. Stockfish and Elmo played at their strongest skill level using 64 threads and a hash size of 1GB. AlphaZero convincingly defeated all opponents, losing zero games to Stockfish and eight games to Elmo (see Supplementary Material for several example games), as well as defeating the previous version of AlphaGo Zero (see Table 1).

Their computer used a new form of chip called a "TPU" (Tensor Processing Unit) developed by Google for machine learning tasks.

They also claim their Monte Carlo tree search algorithm is better and more "human like" than the traditional alpha-beta search algorithms -

> We also analysed the relative performance of AlphaZero’s MCTS search compared to the state-of-the-art alpha-beta search engines used by Stockfish and Elmo. AlphaZero searches just 80 thousand positions per second in chess and 40 thousand in shogi, compared to 70 million for Stockfish and 35 million for Elmo. AlphaZero compensates for the lower number of evaluations by using its deep neural network to focus much more selectively on the most promising variations – arguably a more “human-like” approach to search, as originally proposed by Shannon. Figure 2 shows the scalability of each player with respect to thinking time, measured on an Elo scale, relative to Stockfish or Elmo with 40ms thinking time. AlphaZero’s MCTS scaled more effectively with thinking time than either Stockfish or Elmo, calling into question the widely held belief that alpha-beta search is inherently superior in these domains

Here are some of the games -

```
[FEN ""]
[White "Stockfish "]
[Black "AlphaZero"]

 1. e4 e5 2. Nf3 Nc6 3. Bb5 Nf6 4. d3 Bc5 5. Bxc6 dxc6
 6. O-O Nd7 7. Nbd2 O-O 8. Qe1 f6 9. Nc4 Rf7 10. a4 Bf8 11. Kh1 Nc5 12. a5 Ne6
 13. Ncxe5 fxe5 14. Nxe5 Rf6 15. Ng4 Rf7 16. Ne5 Re7 17. a6 c5 18. f4 Qe8
 19. axb7 Bxb7 20. Qa5 Nd4 21. Qc3 Re6 22. Be3 Rb6 23. Nc4 Rb4 24. b3 a5
 25. Rxa5 Rxa5 26. Nxa5 Ba6 27. Bxd4 Rxd4 28. Nc4 Rd8 29. g3 h6 30. Qa5 Bc8
 31. Qxc7 Bh3 32. Rg1 Rd7 33. Qe5 Qxe5 34. Nxe5 Ra7 35. Nc4 g5 36. Rc1 Bg7
 37. Ne5 Ra8 38. Nf3 Bb2 39. Rb1 Bc3 40. Ng1 Bd7 41. Ne2 Bd2 42. Rd1 Be3
 43. Kg2 Bg4 44. Re1 Bd2 45. Rf1 Ra2 46. h3 Bxe2 47. Rf2 Bxf4 48. Rxe2 Be5
 49. Rf2 Kg7 50. g4 Bd4 51. Re2 Kf6 52. e5+ Bxe5 53. Kf3 Ra1 54. Rf2 Re1
 55. Kg2+ Bf4 56. c3 Rc1 57. d4 Rxc3 58. dxc5 Rxc5 59. b4 Rc3 60. h4 Ke5
 61. hxg5 hxg5 62. Re2+ Kf6 63. Kf2 Be5 64. Ra2 Rc4 65. Ra6+ Ke7 66. Ra5 Ke6
 67. Ra6+ Bd6 0-1

```

Game

```
 [FEN ""]
 [White "Stockfish "]
 [Black "AlphaZero"]

 1. e4 e5 2. Nf3 Nc6 3. Bb5 Nf6 4. d3 Bc5 5. Bxc6 dxc6 6. O-O Nd7 7. c3 O-O
 8. d4 Bd6 9. Bg5 Qe8 10. Re1 f6 11. Bh4 Qf7 12. Nbd2 a5 13. Bg3 Re8 14. Qc2 Nf8 15. c4 c5 16. d5 b6 17. Nh4 g6 18. Nhf3 Bd7 19. Rad1 Re7 20. h3 Qg7 21. Qc3 Rae8 22. a3 h6 23. Bh4 Rf7 24. Bg3 Rfe7 25. Bh4 Rf7 26. Bg3 a4 27. Kh1 Rfe7 28. Bh4 Rf7 29. Bg3 Rfe7 30. Bh4 g5 31. Bg3 Ng6 32. Nf1 Rf7 33. Ne3 Ne7 34. Qd3 h5 35. h4 Nc8 36. Re2 g4 37. Nd2 Qh7 38. Kg1 Bf8 39. Nb1 Nd6 40. Nc3 Bh6 41. Rf1 Ra8 42. Kh2 Kf8 43. Kg1 Qg6 44. f4 gxf3 45. Rxf3 Bxe3+ 46. Rfxe3 Ke7 47. Be1 Qh7 48. Rg3 Rg7 49. Rxg7+ Qxg7 50. Re3 Rg8 51. Rg3 Qh8 52. Nb1 Rxg3 53. Bxg3 Qh6 54. Nd2 Bg4 55. Kh2 Kd7 56. b3 axb3 57. Nxb3 Qg6 58. Nd2 Bd1 59. Nf3 Ba4 60. Nd2 Ke7 61. Bf2 Qg4 62. Qf3 Bd1 63. Qxg4 Bxg4 64. a4 Nb7 65. Nb1 Na5 66. Be3 Nxc4 67. Bc1 Bd7 68. Nc3 c6 69. Kg1 cxd5 70. exd5 Bf5 71. Kf2 Nd6 72. Be3 Ne4+ 73. Nxe4 Bxe4 74. a5 bxa5 75. Bxc5+ Kd7 76. d6 Bf5 77. Ba3 Kc6 78. Ke1 Kd5 79. Kd2 Ke4 80. Bb2 Kf4 81. Bc1 Kg3 82. Ke2 a4 83. Kf1 Kxh4 84. Kf2 Kg4 85. Ba3 Bd7 86. Bc1 Kf5 87. Ke3 Ke6 0-1

```

White: AlphaZero Black: Stockfish

```
 [FEN ""]
 [White "AlphaZero "]
 [Black "Stockfish"]

 1. Nf3 Nf6 2. c4 b6 3. d4 e6 4. g3 Ba6 5. Qc2 c5 6. d5 exd5 7. cxd5 Bb7 8. Bg2 Nxd5 9. O-O Nc6 10. Rd1 Be7 11. Qf5 Nf6 12. e4 g6 13. Qf4 O-O 14. e5 Nh5 15. Qg4 Re8 16. Nc3 Qb8 17. Nd5 Bf8 18. Bf4 Qc8 19. h3 Ne7 20. Ne3 Bc6 21. Rd6 Ng7 22. Rf6 Qb7 23. Bh6 Nd5 24. Nxd5 Bxd5 25. Rd1 Ne6 26. Bxf8 Rxf8 27. Qh4 Bc6 28. Qh6 Rae8 29. Rd6 Bxf3 30. Bxf3 Qa6 31. h4 Qa5 32. Rd1 c4 33. Rd5 Qe1+ 34. Kg2 c3 35. bxc3 Qxc3 36. h5 Re7 37. Bd1 Qe1 38. Bb3 Rd8 39. Rf3 Qe4 40. Qd2 Qg4 41. Bd1 Qe4 42. h6 Nc7 43. Rd6 Ne6 44. Bb3 Qxe5 45. Rd5 Qh8 46. Qb4 Nc5 47. Rxc5 bxc5 48. Qh4 Rde8 49. Rf6 Rf8 50. Qf4 a5 51. g4 d5 52. Bxd5 Rd7 53. Bc4 a4 54. g5 a3 55. Qf3 Rc7 56. Qxa3 Qxf6 57. gxf6 Rfc8 58. Qd3 Rf8 59. Qd6 Rfc8 60. a4 1-0

```
> 14 votes

# Answer
Ok, I have to admit that I was wrong. Though I would maintain that it was due to knowledge of the expert opinion, not general obtuseness: To cite the paper: "However, chess programs using traditional MCTS were much weaker than alpha-beta search programs, (4, 24); while alpha-beta programs based on neural networks have previously been unable to compete with faster, handcrafted evaluation functions."

Apparently, chess is strategically deep enough, that you can out strategise somebody, who would be able to out calculate you. To me that's a big surprise because the development in chess engines had been going in the opposite direction. (Apparently there is still a slight caveat as to whether AlphaZero is really stronger than Stockfish: Stockfish played with just 1gb for the hashtables and 64 cores may not really be a match for four TPUs)

It's also a really, really exciting thing to happen, because AlphaZero very likely has very different strengths from traditional engines.

It also means that I update my belief of the significance of AlphaGo as a technological breakthrough by a lot. Basically smashing shogi, Go and chess with one single setup is completely amazing, not to mention dozens of other games that could likely be played on a superhuman level by AlphaZero.

There is a nice explanation as to why MCTS is actually a decent idea even for chess compared to alpha-beta search (from the paper): "AlphaZero evaluates positions using non-linear function approximation based on a deep neural network, rather than the linear function approximation used in typical chess programs. This provides a much more powerful representation, but may also introduce spurious approximation errors. MCTS averages over these approximation errors, which therefore tend to cancel out when evaluating a large subtree. In contrast, alpha-beta search computes an explicit mini-max, **which propagates the biggest approximation errors to the root** of the subtree." (emphasis by me)

Here is my old answer, still containing some valid points, despite the conclusion being superseded by reality.

First of all Alphago is not a general game playing system. It is a program designed purely to play go and nothing else. It is however build from certain building blocks that have a much wider applicability, such as convolutional neural networks, which have been used in image recognition and which have immediate application in medical diagnostics, and reinforcement learning which was used to master the Atari games mentioned in the article.

Also, current engines do "learn" by self-playing: "Overnight, Lefler’s six computers play through over 14,000 games each during an eight-hour period. “Six machines times 14,000 games is a lot of games,” he says. And with every game played, the database gets deeper and richer. There is even sporting interest in watching computers play against one another The result of Lefler’s busily whirring machines is the ever-increasing prowess of Komodo."

To come to the bulk of your question:

There is an important difference between chess and go, at least from a programmer's perspective. Chess is more of a tactical game, whereas go is more of a strategic game. This means that in chess calculation depth trumps positional evaluation. That's basically the key insight that distinguishes the "old" engines like Fritz, Shredder, Junior and the newer generation like Fruit, Rybka, Houdini, Stockfish, Komodo. Because at the end of each line you have to evaluate the position and you want to calculate lot's of lines and the quality of the evaluation isn't as important as search depth, chess engines have lean and fast evaluation functions.

In go on the other hand the tactical complexity is too big even for computers. Consequently evaluating positions and moves accurately is key. What Alphago brings new to the game is this evaluation power, which is based on convolutional neural networks.

To finally get to my point: Whereas chess evaluation functions are lean and fast, neural networks have millions, sometimes billions of parameters. Because "learning" in this context means tweaking parameters, there is much more possible progress for self learning go programs.

So, yes you could use a setup like Alphago to create a chess engine, but it wouldn't be particularly good. Running the evaluation function would take so much time, that you'd have to utilise a huge cluster of gpus to get to necessary search depths (which is what Alphago does). You could create a very good evaluation function, but the speed tradeoff isn't worth it.
> 10 votes

# Answer
There is a project called spawkfish that attempts to do just this. It is a neural network-based engine whose purpose "is to explore how recent advances in computer Go can be applied to the world of computer Chess".

It is a young project and the engine is still quite weak. Playing it is interesting, because its positional play is better than its tactics.
> 5 votes

# Answer
> Can a similar AI win at chess? Can it achieve pure self-training?

The short answer is "No!"

Chess and go are radically different in their relative simplicity and relative complexity which derives from their geometry and how you win. These combine to make a program which is good at one useless at the other.

In chess you win by checkmating the opponent, points don't count. Of course a sensible opponent will often resign before you deliver checkmate but the principle is the same. In go you win by having more points at the end of the game. If I have a king and queen and you have a king, rook and pawn but you have built a fortress then it doesn't matter that I have 9 points for the queen and you have just 6 points for your rook and pawn. The game is a draw.

This makes a fundamental difference in the complexity between chess and go. In go you can just keep score and you will know who is winning. In chess the only way you can know who is winning is by pure calculation. In this sense chess is much more complex than go.

At the same time, because of the geometry of the two games, there are orders of magnitude more possibilities in go than in chess. In this sense go is much more complex than chess.

A chess program works by brute force calculation of all the possible moves up to a certain depth which determines its strength. A go program cannot work like this and play anything more advanced than beginner level go.

The basic aim of go is to control more territory than your opponent. At the end of a game it doesn't matter if the difference is 1 stone or 100 stones, both are wins. Every time you place a stone you do two things. You increase your territory, either potential or actual, and you decrease your opponent's.

Sometimes, when it is actual increase or decrease in territory, it is easy to calculate the value of the move, but when it is potential it is very difficult to evaluate. As a weak go player I understand the "actual" much better than the "potential" and a stronger player will beat me by building much greater potential territory in the center while I build smaller actual territory on the edges and in the corners. The stronger player will have built up the ability to judge through intuition and feel from playing lots of games and recognizing how to build "potential" territory.

Earlier I said that every time I place a stone it increases my territory (actual or potential) and decreases my opponent's (actually if it is a stupid move it will do the opposite!). In any given position not all moves are the same. A stone placed in one position can be worth much more or much less than a stone placed in another.

Typically in a game there will be small "fights" where players place their stones near each other, marking out their territory and limiting their opponent's. Meanwhile there are possibilities to start staking out territory in another part of the board or switch to a fight somewhere else where both players already have stones.

What is very important in these situations is knowing when to stop one fight, because the potential gains have diminished, and to either switch to another fight or perhaps strike out into virgin territory. Sometimes this depends on hard calculation but often it is much more nebulous and not subject to calculation. As a weak player this is where a strong payer will crush me every time.

What the computer does in these situations is use probabilistic methods to generate an expected score for a particular move. Sometimes the actual value will turn out to be a little bit less, sometimes a little bit more but over the long haul it will even out more or less. It will keep picking the move with the highest expected value with the expectation that over the long haul of a game small errors will cancel out and its strategy will win.

This is not a strategy which sounds familiar to chess players and is not one which is going to work in chess. It is something which sounds familiar to anybody who follows what goes on in the share markets. It sounds very similar to something called "high frequency trading" where computers will make thousands of small bets or just proposed bets every second to "nickel and dime" the market and perhaps even to move it very marginally in their favor over periods of milliseconds.

Already the financial markets are dominated by these kinds of algorithmic trading which suggests that this kind of program has already triumphed in a far more lucrative area than a board game.
> 4 votes

# Answer
(Anyone how wants a deep technical discussion for AlphaGo can look at my post)

**Short answer**: No

**Long answer**:

First, we need to understand why Google didn't implement alpha-beta into AlphaGo. Stockfish and Komodo (and all chess engines) have alpha-beta, why wouldn't AlphaGo?

**Reason**: there is no easy and cheap way that can accurately evaluates a Go position statically.

In Chess, we can always count the materials, a very effective way to evaluate a position statically. Although not perfect, it's very fast and a very good proxy for chess.

Searching the state space with Monte-Carlo is an **inferior** method to alpha-beta. Google would have implemented alpha-beta if they could, but they couldn't. Thus, they were forced to use something much slower.

Chess engine would not play better with Monte-Carlo.
> 4 votes

# Answer
I disagree with the other answers. I am computer scientist who works professionally in the area of artificial intelligence and am also a candidate master in chess and 3 dan in igo.

I think it is unclear at this time whether Deep Mind's methods could be applied to chess, but I think it is possible.

Currently, the top chess-playing programs are increasingly relying on heuristics and attempting to use the AlphaGo architecture for chess would in some ways be in the same line of thinking.

One key architectural feature of AlphaGo that would have to be altered is its method of identifying key squares (or heat maps), which is particular to igo-like games and is not directly applicable to chess. Some analog of this method would have to be developed to make the AlphaGo architecture relevant to chess. For example, we could have the concept of "key pieces" rather than key squares.

I think the argument that the AlphaGo architecture is not relevant to chess because chess is more tactical is not a very good claim because ultimately both have search trees which are similar enough in shape that AlphaGo could definitely be adapted to chess.
> 4 votes

# Answer
The answer is Yes! Google just proved this yesterday, when AlphaZero beat the best chess program using only knowledge about the rules and pure self training with no human chess knowledge used. The accepted answer is wrong. The link to the article is here :link
> 3 votes

# Answer
To see AlphaZero in action, follow http://lczero.org/ or play at http://play.lczero.org/
> 0 votes

---
Tags: engines
---


# Question
Title: Can a king be checked with another king when checking square is protected by the side which gives the check?
Can a white King move next to a black King to check it, if there is a white pawn protecting the white King, preventing the black King from taking the white King?

# Answer
Hi David and welcome to chess.stackexchange.com. This is a common question.

It's illegal to move a king into check, or to leave it in check. This includes moving a king adjacent to the opposing king. If you have no legal moves then the game is over: if your king is in check then you are checkmated and you have lost, otherwise you are stalemated and the game is drawn. This is basic to chess, and doesn't require any particular Laws.

If you want chapter and verse, you can find it in the FIDE Laws (which operate in all parts of the world apart from USA) Articles 1.4.1 & 3.9.2. While reading Article 1.4.1, you might also notice that it's illegal to capture the opponent's king. You might reflect that this is a curious rule in two respects (a) it can never apply in a legal position - because it would have been illegal for the opponent to have left his king in check! (b) it would never be a good move to capture the opponent's king - because then you could never checkmate it! You would be right in this reflection, but the rule is there to stop things get too crazy if an illegal move isn't spotted immediately.

To summarize: you can *never* move so that your king is in check, even if the king is "protected".
> 13 votes

# Answer
This is an illegal move. Even if the White King is protected, you can never put your King en prise.

However, if you were to play such a move and your opponent didn't call it ON THAT MOVE, an interesting scenario arises. Under the FIDE handbook, section 7.5.1, it says that if an illegal move happens during a game, the position before it will be reinstated. So, assume White moves his King to c6 (illegal) and Black didn't call it and moved his King to b6 (also illegal in this instance). If White THEN called Black for his illegal move to b6, the game would be reinstated to the position before White moved his King to c6 (the first illegal move that happened in the game).

Link to the FIDE Handbook:

https://www.fide.com/fide/handbook.html?id=208&view=article
> 7 votes

# Answer
Your movement is not valid because you are giving up your white King. It does not matter if you counter-attack with the pawn after losing your king. The match is won by the player who first takes the King.

There are questions related to yours, for example Can a piece pinned to my king put the opponent's king in check?
> 4 votes

---
Tags: rules, check, illegal-move
---


title: Why does Stockfish prefer White here?

text:
# Question
Title: Why does Stockfish prefer White here?
My analysis of the position:

1. Materially, black is a pawn up.
2. White's rooks and bishop are active.
3. White has potential counterplay on Black's Kingside but I think it can be defended by the move Ng6.
4. Black's queen is active.

According to my analysis, the position is quite equal and I don't find any reasonable justification for stockfish's score.

Can you please explain why does stockfish prefer white here?

# Answer
> 6 votes
The key is to see how quickly both sides can bring their pieces into the game. Only Black's Queen and Knight are active -- his Bishop and two Rooks are extremely passive and can only be activated after many moves.

Meanwhile, White's Rh2 is active and he can bring Ra1 into the game in one move (by playing Rg1). Qc2 seems passive, but it can be opened quickly by playing d4, and maybe even a pawn sac with e5. White can bring the Knight into the game by playing Nf3, and the Bishop can be activated on the same diagonal as the Queen, after a potential pawn sac with e5.

Also, notice how by playing d4, White drives away one of Black's two active pieces. As an extra bonus, d4 also gives White full control of the center, and limits Black's Bishop.

Based on all this, White has more than enough compensation for the h6-pawn (which can't even move without being taken), but not enough to be winning (just better).

# Answer
> 7 votes
The main feature in this position is the lack of defenses around black's king. After Rg1 followed by improving the bishop, either h5 or c4 to pressure f7, you are effectively attacking with an extra rook.

Some sample attacks are:

1) Although a beginner's attacking formation, aligning a queen-bishop battery--by d4, Qd3, Bd1-c2, threatens a simple mate on h7.

2) After an exchange sacrifice on g6, the weakness on the white squares are easily exploited after the bishop gets to c4.

3) After the Knight reaches f5, via Nf1-e3, the pressure on g7 and especially h6 is difficult to protect.

The knight on g6 is the king's best protector, but, mainly due to it being on a white square, it is easily removed, and then black's kingside becomes exposed.

# Answer
> 0 votes
Since this is an opposite-colored bishop game, black has a light squared weakness on both sides, which could lead to an invasion on the light squares from white.

Even though White doesn't have any pawns to protect the White King, it does provide semi-open files for the rooks to attack on, and the semi-open files lead straight to the black king.

---
Tags: stockfish, positional-play
---


# Question
Title: Are there any legal positions known to be impossible to come to in a normal game?
There are some fairly obvious ways to set up a chess board that cannot possibly happen: both kings simultaneously in check would be one.

There are some positions that *seem* impossible in a normal game... for example, one side has all of it's original pawns in their original location and the other side has NONE of its pawns remaining - but with both sides displaying all pieces in their original positions (perhaps knights can do this, I don't know.)

However, seems like there may be some impossible positions *that are not at all obviously difficult.*

The question is if there are any known legal positions (preferably ones that a normal human might think are the result of a game) that cannot be played into?

# Answer
> 5 votes
Hi and thanks for the question. The words "legal" and "illegal" are actually defined in the FIDE rules. Basically, a legal position is one which can be reached by a sequence of legal moves.

So, with this definition, I think that you are asking: are there illegal positions which aren't obvious? The answer is "many" Welcome to retrograde analysis! :D

There is already a chess.stackexchange question on this, so I suggest we continue the discussion there: Are there any illegal positions that are difficult to spot?

---
Tags: rules, illegal-move, retrograde-analysis
---


# Question
Title: What are the differences that a beginner should be aware of between opening with 1.e4 or 1.d4?
I am preparing for a tournament, so which opening should I use or prepare? How can I become strong in a specific opening line?

# Answer
> 3 votes
Tough to tell

**Benefits of Both**

d4 is very strong controlling two central squares (e5 and c5) e4 controls 1 (d5 since f5 doesn't help develop pieces it's not the best)

e4 opens up the white bishop and queen diagonals (Though queen's is easily blocked), while d4 opens up the bishop, d4 is also benefit by being naturally guarded by the queen.

**Analysis of Both**

I personally find d4 to be better at gaining control of the center, especially with my favorite white opening, the queen's gambit. Since black can't attack the e pawn black is forced to develop slower since it can't openly attack the center. In this case, d4 is solid.

e4 on the other hand promotes more activity from other pieces by opening up the two diagonals (Though the queen's is almost never used). Yet, since this allows black to fight for the center I have found more exchanges, and I like using e4 for creative openings such as the Ruy Lopez, Rio Gambit, or learning the Sicilian lines seizing space as white while black has to open up space for his pieces to develop.This makes e4 a very good way to open the board, though this opens up many weakness for white often in exchange for black's lack of development.

**My Opinion**

At high level play, the Sicilian is threatening and at GM-level play e4 has a very low win rate compared to d4 (Refer to Stat's section). It lacks the solid control of the center and e4 promotes a large amount of counter-play, though in my opinion, it doesn't matter at the moment. It's nice to play both and find your own comfort and flexibility.

**Recommended Openings**

If you are looking for lines to learn my top 3 for white (in order favorite-least) are: Queen's Gambit, English Opening, and for Black: Sicilian, Nimzo-Indian, and Modern Defense. These are solid and work great at tournament level play.

---

**Stats**

Chess.com's Opening Explorer (https://www.chess.com/explorer) documents e4 as having (38% wins, 32% ties0, 30% losses) with 879,507 recorded games. d4 is recorded as having (39% wins,34% ties,27% losses) with 693,538 games archived. While this is a fairly close margin the major notable point is the 3% deviation of loss rates, but these ideas aren't imperative as they encompass all levels of play.

The World Championship test Another method to compare these two moves, using actual facts and information instead of general ideas, is to observe the world championships. In a world championship, the players prefer the move they consider more beneficial; the move they believe will offer them more opportunities to achieve victory (especially when playing white). The contenders have, of course, practiced time and again and every defeat signifies a major weakness. What is more, world championships constitute a great study sample simply because there is no other tournament where players demonstrate such seriousness and concentration. Let us examine the results of the modern chess era, meaning the most recent world championships, starting from the year 2000 when Kramnik became world champion.

"In 89 games 1.e4 was used 25 times resulting in: only one win, three losses and 21 draws. In 89 games 1.d4 was used 62 times resulting in: 18 wins, 6 losses and 38 draws. 1.e4 wins: 4% losses: 12% draws: 84% 1.d4 wins: 29% losses: 9% draws: 61%"

(https://en.chessbase.com/post/1-e4-or-1-d4-which-is-the-better-move)

At championship level play there is a drastic deviation between the openings, nearly 25%.

---
Tags: opening
---


# Question
Title: Encyclopaedia of chess openings in machine readable form
I am building an app that allows the user to track openings in visual form. They will make moves on the board and the name of the opening and common next moves will be displayed. Now I need some data to do this. First is a database of games to search so I can work out the most common next moves. This I have done by downloading PGN files.

Secondly, I need data on the opening names. I understand there is an Encyclopaedia of Chess Openings which has named and categorised thousands of openings. Does anyone know if this encyclopaedia is available in machine readable form (eg an xml or db file)? Either free or for a small fee?

# Answer
SCID has a text file that you can use. It begins like this:

```
# scid.eco
#
# Encyclopaedia of Chess Openings file for Scid vs. PC
#
# Copyright (C) 1999- Shane Hudson and others.
# Last updated: Febuary, 2014
#
# In addition to standard ECO definitions, scid.eco allows for extensions:
# Each basic code can have a lower case letter extension (a-z), and an extra
# level (1-4). So the order of ECO codes for A00 is:
# A00, A00a, A00a1, A00a2, A00a3, A00a4, A00b, A00b1, ..., A00z4.
#
# You can convert this file to PGN format with the "eco2pgn.py" script,
# and to EPD with the "eco2epd" (use "make eco2pgn").

A00a "Start"  *
A00b "Barnes Opening"  1.f3 *
A00b "Fried fox"  1.f3 e5 2.Kf2 *
A00c "Kadas Opening"  1.h4 *
A00d "Clemenz Opening"  1.h3 *
A00e "Ware Opening"  1.a4 *

```
> 12 votes

---
Tags: opening, eco
---


title: On the Mason Attack

text:
# Question
Title: On the Mason Attack
What are the main points, tactical or otherwise, backing up the Mason Attack?

I got the idea reading about the London System, but the Lichess engine calls it "Mason Attack". It starts out as follows:

```
[FEN "rnbqkbnr/ppp1pppp/8/3p4/3P1B2/8/PPP1PPPP/RN1QKBNR b KQkq - 1 2"]

```

I always try to achieve the following position, which I judge fairly solid and with good attacking chances on the King side (don't mind Black moves in this case -- it's just one of the many possible lines for Black):

```
[FEN "r2q1rk1/1ppb1ppp/p1nbpn2/3p4/3P4/2PBPNB1/PPQN1PPP/R3K2R b KQ - 2 9"]

```

I'm asking since I've enjoyed great success with this opening, but I cannot find much research about it. As a very beginner I don't exactly know how to analyze openings with Stockfish since it always gives the best lines, which I rarely encounter in practical play. Example games of mine:

```
[Site "https://lichess.org/r2ujDJpt"]
[Date "2018.04.03"]
[Result "1-0"]
[UTCDate "2018.04.03"]
[UTCTime "10:26:29"]
[FEN ""]

1. d4 Nf6 { A45 Indian Game } 2. Bf4 e6 3. e3 d5 4. Nf3 c5 5. c3 Nc6 6. Nbd2 Qb6 7. Qc2 Bd7 8. Be2 cxd4 9. exd4 Be7 10. h3 O-O 11. g4 a5 12. g5 Ne8 13. h4 Bd6 14. Be3 Nc7 15. h5 a4 16. a3 Na5 17. g6 fxg6 18. hxg6 h6 19. Bxh6 gxh6 20. Rxh6 Kg7 21. Rh7+ Kf6 22. Rxd7 { Black resigns. } 1-0

```

.

```
[Result "1-0"]
[UTCDate "2018.02.23"]
[UTCTime "12:10:06"]
[FEN ""]

1. d4 d5 2. Bf4 { D00 Queen's Pawn Game: Mason Attack } Nc6 3. e3 Bf5 4. c3 Nf6 5. Nd2 e6 6. Ngf3 Bd6 7. Bg3 Bxg3 8. hxg3 Ne7 9. Ne5 Ng6 10. g4 Nxe5 11. gxf5 Nc6 12. fxe6 fxe6 13. Bd3 h6 14. e4 O-O 15. e5 Nd7 16. Rxh6 Qg5 17. Rg6 Qf4 18. Qe2 Nb6 19. O-O-O Na5 20. Rh1 Nac4 21. Rh8+ Kxh8 22. Qh5+ Kg8 23. Rxg7+ Kxg7 24. Qh7# { White wins by checkmate. } 1-0

```

# Answer
> 5 votes
> What are the main points, tactical or otherwise, backing up the Mason Attack?

At least for normal (not top GM) players, the main points of the London system (never heard the name Mason Attack before), is to just get out the pieces to natural squares and take it from there. White is not really aiming for an immediate advantage. Pieces are not exchanged which can potentially lead to more rich positions later on. This can potentially favor the stronger player as it avoids drawish limited material/symmetric positions.

As you note, you can play this against just about anything that black does (so called "system opening"), which is another advantage for players who don't want to be bothered studying theory.

Typical middlegame plans can be a kingside attack supported by queen/bishop along the b1-h7 diagonal, various pawn breaks (e.g. with e4, c4), or play on the queenside supported by the bishop on the h7-b8 diagonal.

As for analyzing this or any other openings with a computer engine: This is really only useful if you know the opening very well and are looking for novelties, etc, so basically only for players around GM level.

For more mortal players, time is spent better by following (preferably annotated/commented) games of top players in that opening and see what plans or ideas they develop.

You can still use an engine to point out tactical errors in your own games including the opening phase, but they are not all that useful for finding the "best" move in the opening. To elaborate on this, openings are still too complicated for engines to find the objectively best move, since basically any evaluation of normal opening positions will be around 0.0. As a human you are not looking for the objectively best move anyway, but for the line that gives you positions that you are comfortable playing (and that are difficult to play for your opponent). There is no point going down a line that gives you a centipawn advantage if you have to make 20 accurate quiet (non-forced) moves or otherwise be lost.

---
Tags: opening, 1.d4, london-system
---


# Question
Title: Where can I find learning material on how to play the Alekhine-Chatard Gambit Declined?
I'm looking for materials on how to play the Alekhine-Chatard Gambit Declined. Which books and references are available for this variation? I'm looking for possible good moves to play for when this gambit is declined.

# Answer
May I suggest a game I recently played over the board to equality? Both my opponent and I are 1680-ish FIDE-rated. I don't know the theory of this line yet, so moves were found over the board.

```
[FEN ""]
1. e4 e6 2. d4 d5 3. Nc3 Nf6 4. Bg5 Be7 5. e5 Nfd7 6. h4 a6 {I went into a long think here, but a6 is necessary to prevent the knight from entering from the flank, if Black plays an early c5 now} 7. Bxe7 Qxe7 8. Qg4 f5 9. Qg3 c5 10. Nf3 Nc6 11. O-O-O cxd4 12. Nxd4 Nxd4 13. Rxd4 Nc5 14. Bd3 Nxd3+ 15. Qxd3 O-O 16. Qe2 Bd7 17. g4 Rac8 18. gxf5 Rxf5 19. Rg1 Bb5 20. Nxb5 axb5 21. Rdg4 Rf7 22. Qxb5 Qc7 23. Qe2 Qc5 24. f4 g6 {Rxf4 now is tempting, but Black would get checkmated via Rxg7+ Kh8 Rxh7+ Kxh7 Qh5#} 25. h5 Rxf4 26. hxg6 h6 27. R4g2 Kg7 28. Rh1 Re4 29. Qd2 Qe3 1/2-1/2

```

And Chess History page has this http://www.chesshistory.com/winter/extra/french.html
> 3 votes

---
Tags: opening, gambits, french-defense
---


# Question
Title: What are weak squares in chess; how can they help to mate another player?
I read this concept in a book but I didn't understand much about the concept. Can anybody explain this concept with an example?

# Answer
> 6 votes
This is a very common example.

```
[FEN "6k1/5p1p/5BpQ/8/8/8/8/6K1 w - - 0 1"]

```

Do you see the weak dark squares around the king? Checkmate is possible because those squares are weak and can't be defended.

# Answer
> 4 votes
*A weak square is a square of great great importance that is difficult to cover or get rid of.*

---

Since the square is difficult to cover, it can become a great outpost for opponent's (your) pieces, usually a knight.

If you manage yo get the right piece on that square, it helps you in any kind of possible attacks. Whether the attack will result in checkmate or 'only' material advantage depends on the position.

---

It usually doesn't matter, whether there's a pawn on that square or not (as A. Nimzowitsch stated). You will have the same problems/advantages connected with it.

The only difference is that the pawn can be targeted for the sake of capturing it.

---

Recap:

There are 2 basic ways to take advantage of a weak square

1. Occupy it to get good outposts for your pieces and to get control over certain parts of the board.
2. Attack and capture the weak pawn

Note: Usually 1 weakness isn't enough to win the game, the opponent will be able to protect it. The principle of 2 weaknesses says that you have to find at least another one.

---
Tags: theory, books
---


title: The strength of blind chess players

text:
# Question
Title: The strength of blind chess players
Before I begin, I'm not asking about people playing "Blindfold chess", but those who are actually blind.

Reading through the FIDE rules of chess like any good player should, I've previously noticed the section containing rules for players who are visually handicapped. I never really paid this any attention before other than to note how difficult it must be to both learn the game (containing as it does complex spatial movements and a large amount of information to be kept in the head if it cannot be seen) and to study it (most learning resources being books that are probably nowhere near popular enough to be made 'accessible').

Just recently I started thinking about this, and I'd like to know a bit more about this aspect of the game, but information is rather hard to find. To begin with, **How strong are the strongest blind chess players in comparison to those without disability?** Ideally we'd be talking about people using the same scale (i.e. theoretically entering the same 'ordinary' tournament with perhaps minor allowances for the games of the disabled person, and needing to have comparable Elo ratings, etc.), though if there's a separate rating system that information would be useful too.

On a related note, **Have there been any blind players notable for their strength or players they have faced?**

# Answer
According to this link, the World Blind chess championship includes IM-strength players.

A separate rating system isn't used but one cannot accurately compare ratings from two different player pools.

According to this link, the 2009 Blind US champion was a USCF Expert.

Roughly, I'd say being blind costs 600 rating points. Why? An USCF Expert is around 2100, the USCF National champion is about 2800, so subtraction gives 700. Similarly, a super-GM has about 450 more ELO points than an IM (2400 vs 2850) 700... 450... call it 600...)
> 6 votes

# Answer
I believe Stanislav Babarykin is the current (or former) world champion among blind chess players and his rating is around 2350.

In my country India, arguably the strongest (blind) player is Darpan Inani (rated 2041).

So while the current strongest blind chess players are not in the GM category, it is also the case that there are very few such players.
> 6 votes

# Answer
I played a blind player with a high expert rating in the 1970s. He said that going blind cost him about 200 rating points. His play was very strong but then he would miss things that I don't think a sighted player would.
> 3 votes

# Answer
At the 15th IBCA Chess Olympiad for Blind and Visually Impaired Chess Players 2017, the best player was the polish GM Marcin Tazbir (2525 in April 2018).

Here is the list of the 10 best rated players in this event.

1. GM Tazbir Marcin 1122452 2514 POL POLAND
2. Smirnov Alexey 4168437 2427 RUS RUSSIA
3. IM Tuka Oleg 14114453 2407 UKR UKRAINE
4. IM Pakhomov Alexey 4129016 2350 RUS RUSSIA
5. FM Dimic Pavle 937428 2349 SRB SERBIA
6. FM Babarykin Stanislav 4101898 2332 RUS RUSSIA
7. IM Meshkov Yuri A. 4107101 2328 RUS RUSSIA
8. FM Suslov Evgeniy 24149411 2313 RUS RUSSIA
9. IM Nikac Predrag 908975 2308 MNE MONTENEGRO
10. FM Magnusson Jorgen 1700880 2290 SWE SWEDEN
> 3 votes

---
Tags: rating
---


# Question
Title: Claiming a 50-move draw with a mating move
Under FIDE law 9.3.1, a player to move may claim a 50-move draw by writing down the intended 50th move and making the claim.

Supposing this claim is otherwise valid; if the move would checkmate then is the game drawn?

# Answer
Mate ends the game immediately, but the mating move must be *made*, not just written down. If the player only writes the move down and claims a draw in the correct way, it's a draw (but I doubt it'll ever happen in practice).
> 3 votes

---
Tags: rules, checkmate, 50-move-rule, claim-draw
---


# Question
Title: What is the order of actions in chess under FIDE rules?
Reading some recent posts about the 50 move rule made me realize that I've never seen an explicit order of actions for chess. By way of comparison, the order of actions in Monopoly is given here:

```
(1) Throw the dice
(2) Move the indicated distance or to jail (if 3rd double in a turn)
    - collect $200 if land on or pass Go
(3) Resolve space
    - ownable properties
        = pay rent if owned and not mortgaged
        = buy it if unowned (optional)
        = auction property if still unowned (not optional)
    - non-ownable properties
        = resolve as indicated.
        = collect $200 if resolving puts you passing Go.
(4) Pass the dice or roll again, as appropriate.

```

A chess move combines three actions (shifting wood, writing move, hitting clock) and the game can end in various ways (mate, stalemate, dead position, agreement, 50 move rule, 3-fold repetition, 75 move rule, 5-fold repetition). For simplicity, let's put to one side for now resignation & irregularities e.g flagfall).

# Answer
The FIDE Laws of Chess provide some guidance.

Rule 6.2.1 says you must move the piece before hitting the clock:

> During the game each player, having made his move on the chessboard, shall stop his own clock and start his opponent’s clock (that is to say, he shall press his clock). This “completes” the move.

According to rule 8.1.2, you must move the piece before writing down the move, usually:

> It is forbidden to write the moves in advance, unless the player is claiming a draw according to Article 9.2, or 9.3 or adjourning a game

There is a little bit of flexibility as to when exactly you write down the moves, according to 8.1.3:

> A player may reply to his opponent’s move before recording it, if he so wishes. He must record his previous move before making another.

So, you must move the piece before doing anything else. Ordinarily, you would then hit the clock, and finally you would write down the move. I am not sure if it would be a violation of 8.1 to write the move after moving the piece but before hitting the clock - technically, the move is not "completed" until the clock is hit - but it gives no benefit to do so. In practice I've only seen it when someone forgets to hit the clock altogether.

Offering a draw is done after making the move but before hitting the clock, and claiming a draw is done by writing down the move but *not* playing it, and seeking the arbiter.

The 5-fold repetition and 75-move rule may be claimed by the arbiter whenever applicable, so you can't really give them any set place in the order.

This gives us the following order:

```
(1) If claiming a draw:
     - Write move (if this move is required for draw)
     - Stop clocks (not required, but wise)
     - Declare draw claim to arbiter
     - If claim is upheld, game is over

(2) Make your move on the board
    - If this move results in checkmate, stalemate, or dead position, game is over

(3) If offering a draw, offer draw to opponent
    - If opponent accepts draw, game is over
    - If opponent declines, or delays decision, proceed to (4)

(4) Press clock
    - (Probably this could be done after (5), but this order is preferred)

(5) Write move

```
> 12 votes

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Tags: rules, checkmate, stalemate, 50-move-rule, threefold-repetition
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title: How is this checkmate?

text:
# Question
Title: How is this checkmate?
So I'm somewhat of a new player to chess and I'm currently reading a chess book which is explaining all the different terms. In one instance it describes what stalemate is; "If your opponent has no legal legal moves and is not I)in check, then you have stalemate and not checkmate"

It then gives an example of stalemate and then a non stalemate example which it labels as checkmate.

The confusion that I have is why it labeled the second one as checkmate. Isn't checkmate when the king piece is in check and there is no legal moves it can make? Thus in the second example it isn't in checkmate because the king can still move around on the 8th rank and there is no immediate danger to it so it isn't in check either... Or does checkmate also include being trapped in a certain row, column or diagonal length with no other moves you can take except to move along those boxes?

# Answer
The position shown in board 2 is not a checkmate, as you correctly say.

The book is not completely clear here. The sentence "Checkmate with Queen and King" is only the task of an exercise: you have to set up the position you see on a real board, and move the pieces trying to checkmate the black king using the white Queen and King. The checkmate is not there yet, you have to play and find it. It is not immediate, it will take some moves.
> 26 votes

# Answer
It's not checkmate.

The 2nd diagram is an example of how to trap the king on the side of the board, while avoiding the stalemate situation in the first.
> 18 votes

# Answer
If you look at Board 2, and it is white's turn, consider what happens if you move the Queen to F7. Or, if it is black's turn, and Black moves to E7, consider what happens if the queen moves to G7.

The answer is that Black will have only one legal move. White can respond each turn by getting one step closer to Black, until White can force the checkmate.

Although, white needs to be careful about this. By reducing Black's movement possibilities by one square each time, white could force Black into a position of placing the King in the corner and getting stuck. That is fine, but white is then required to either checkmate immediately, or provide Black with a little bit of additional leeway to be able to move again, or else White will cause a Stalemate and white will lose the ability to win the game. (At this point, if those are the only pieces on the board, such a Stalemate is the best that black could hope to accomplish. However, Black can't force a stalemate from this position. Black can only hope that White makes an error.)

So Board 2 is not showing Checkmate, but that board may still be useful to think about for educational purposes.

I agree that the book is not abundantly clear, as the way that the book phrases things could be interpreted to suggest that checkmate has been accomplished. However, without question, checkmate has not yet been achieved in Board 2. Board 2 is just showing a somewhat common situation where checkmate can be achieved relatively easily, and soon. In this scenario, if there are no other pieces, white is unlikely to be thinking about defending itself, or how to reduce the number of pieces on the board. Instead, white will be focused on how to obtain checkmate soon, as a realistic short-term goal. Think of "Checkmate with king and queen" as a topic, or better yet, as an instruction, not as a description of what has already been accomplished.

Note: Board 1 is not something I've seen very often. In order to get into that position, Black would need to have been on B8, and the queen place the king into check by moving to B6, and Black move into the corner. This is unlikely, because Black's usual best strategy in this type of scenario is to move as close to the center of the board as possible. Instead, by going into the corner, Black allowed for an easy Checkmate. Although, if white moves to B8 as one of those red arrows suggests, then white will lose the ability to win the game (assuming there are no other pieces), so white should definitely not do that. I think the Red arrows are just trying to show relevant squares where white's queen can attack, thereby demonstrating black's inability to move to those squares.

Direct answers:

> Isn't checkmate when the king piece is in check and there is no legal moves it can make?

Almost. When you say "it", the sentence looks like you're referring to the king.
Checkmate is when the king piece is in check, and there are no legal moves that the player can make. (If the player can legally move a different piece, then it is not Checkmate. Note that any legal move will require getting the King completely out of check.) So if "there is no legal moves" that the king "can make", but if a knight can get in the way of the piece that is threatening the king, then this is not checkmate.

> Thus in the second example it isn't in checkmate because the king can still move around on the 8th rank and there is no immediate danger to it so it isn't in check either...

You have assessed this correctly.

> Or does checkmate also include being trapped in a certain row, column or diagonal length with no other moves you can take except to move along those boxes?

No. Such restrictions have nothing to do with checkmate. If the king gets into the middle of the board, but then gets threatened and the player cannot eliminate that threat, then there can be checkmate even with the king being in a very different location. (Since it takes some time to get the king to the middle of the board, this isn't very common. When it does happen, often the player who is moving that king already has a rather unpowerful army remaining.)
> 5 votes

# Answer
You're right, the second diagram is not checkmate. I think the book was trying to show *how* you should be playing the King + Queen vs King endgame (i.e., use your Queen to cut off Black's King from a safe distance).

When it said "Checkmate with queen and king" it was likely referring to the name of the endgame itself. I agree that the wording is pretty confusing.

The only way to be in checkmate is to have your King trapped and checked, like you stated.
> 1 votes

---
Tags: checkmate
---


title: Checkmate in two moves

text:
# Question
Title: Checkmate in two moves
White to play and checkmate in two moves.

```
[fen "5Kbk/6pp/6P1/8/7R/8/8/8 w KQkq - 0 1"]

```

Is it possible? If so, please write a solution.

# Answer
> 6 votes
1.Rh6

This puts Black in Zugzwang.

If 1...gxh6, 2.g7#

If Black moves the Bishop, 2.Rxh7#

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Tags: checkmate, problems
---


# Question
Title: E.Umnov's chess problem, 1944. Checkmate in two moves
White to play and checkmate in two moves.

```
[title "E.Umnov's chess problem, 1944"]
[FEN "k7/5QK1/3n1pb1/1R1p1r2/5p2/8/1p6/4R3 w KQkq - 0 1"]

```

# Answer
> 7 votes
1.Re4, threatening 2.Ra4#. Black has many possible moves, but all of them allow either Ra4#, Qa2# Qb7#, or Rxe8# (did I miss any?).

(In the spirit of "teaching a man to fish", if you can't solve a checkmate problem and decide to give up, you can always feed it to a chess engine and get an instant answer without having to wait for someone to reply to an online post. For example, try https://lichess.org/analysis ).

# Answer
> 7 votes
Very nice - thanks for posting. The solution is:

> 1. Re4! threat 2. Ra4#
> 1. ... Nc8/Nb7/Nxe4 2. Q(x)b7#
> 1. ... Ne8+/Nxb5 2. R(x)e8#
> 1. ... Nc4 2. Qb7, Re8#
> 1. ... dxe4/d4 2. Qa2#

Note that after 1. ... Nc4, there are two possible mates. This is not generally regarded as a defect because each of them can be found by itself in other lines.

I am really not an expert in these kinds of problems, but I guess the idea is that White begins with two units en prise, and must paradoxically offer up the third for sacrifice as well.

General purpose chess engines can be used to tackle direct mates like this, but they may not pick up all the artistic points (e.g. tries, set play, duals, etc) and will not be applicable to helpmates, selfmates, retros, fairy problems, etc. Specialist problem engines exist, see this Wikipedia page.

EDIT: Of course at one level, all the engines are pointless. The challenge is for the individual to solve the problem by themselves, without tech support. Direct mates in 2 are fairly simple to solve in this way, but the difficulty grows rapidly as the number of moves increases.

One key difference between solving a problem and playing a game of chess is that in the former, one knows that there is a solution, and that probably it's quite artistic. So part of the approach is to hunt for such cool effects. There are also deliberate red herrings which are part of the fun. E.g. a try is a false answer which *nearly* works, but there is just one black move which defeats it. E.g. in the Umnov problem, how should Black respond to 1. Rxb2? The right move is often quiet and paradoxical - apparently giving something to the opponent, but in reality compelling the opponent to create a fatal weakness in their defence.

On the other hand, one beauty of over-the-board chess is that there's no certainty of a winning move existing at all, certainly not within a specific time span. If it's a published position from a game then there is probably a unique move, but it's possibly quite flashy maybe involving a sacrifice to break through a defensive position.

---
Tags: checkmate, problems
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