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Final Answers
© 2000-2018   Gérard P. Michon, Ph.D.

 Andre Dunican Philidor 


The hardest thing in chess is to win a won game.
Frank Marshall   (1877-1944) 
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On this site, see also:

Related Links (Outside this Site)

Play chess online  (free, no registration).
Nalimov Tablebase Server  at  Lokasoft 
Endgame Tablebases Online  by  Kirill Kryukov.
History of Chess:  Earliest Chess Books and References   by  Bill Wall.
Combinative Chess  by  Sarah Beth  (Chess.com, 2015-10-19).
Chess Page  by  Timothy J. Thompson (1993).
Chess Page  by  Thane E. Plambeck (c.1963-).
Medieval European Chess.
Mathematicians Who Play Chess   (ChessManiac.com, 2015-02-02).

Chess Equipment

Chess Piece Sizing Guideline  by  ChessUSA.
The Chess Store   |   Wholesale Chess

Garry Kasparov:  Chess is mental torture (12:01)  KchessK  (2013-10-20).
"Build a Chess Board"   by  Steve Ramsey   | 1 | 2 | 3 | 4 | 5 | 6 | 7 |
"Searching for Bobby Fischer" (1993):  Early life of  Joshua Waitzkin  (1976-).
"Pawn sacrifice" (2014):  Bobby Fisher (1943-2008)  challenges Soviet chess.
"The Oxford Companion to Chess"
David Hooper & Kenneth Whyld  (1984, 1993).


The Noble Game of Chess

(2018-08-07)   Origins of Chess.  Ancient and modern rules.
The old games of  Chaturanga  and  Shatranj.

Apart from  Go,  all ancien board games can all be classified as single-track  race gamesMancala  is purely strategic  (if you're allowed to count the stones in each pit)  but all the others involve an element of pure luck.  Here are the three most notable examples:

  • The Mesopotamian  Royal Game of Ur.  One of the best designs of all time.  It's  played  with two sets of seven pieces  (at most)  racing on a special board of  20 squares  (two symmetrical 14-square tracks sharing an 8-square middle lane).  The game traditionally uses  4  tetrahedral  dice  with two marked corners.  The outcome of a throw is the total number of marked corners landing at the top;  it's  0,1,2,3,4  (respectively with  1,4,6,4,1  chances  in 16).  The exact rules were found on a late-period  clay tablet from the British Museum  deciphered by  Irving Finkel.  [Play online]
  • The Egyptian game of  senet  (the game of passing).  Two sets of  5  pieces,  racing mostly forward on a single 30-square track  (laid out on a 3 by 10 board).  This simple game has been resurrected using the rules reconstructed by the two game historians  Timothy Kendall  and  R.C. Bell (1917-2002).
  • Nard  and  Backgammon  (enhanced with the  doubling-cube).

By contrast,  the early forms of chess didn't involve chance at all and made full use of the two dimensions of the game board.

The earliest recognizable form of chess was called  chaturanga  (or  catur  for short).  It appeared in India,  in the seventh century AD and is first mentioned in the  Harshacharita  (biography of Harsha,  c.590-647)  by  Banabhatta.

Shortly thereafter,  the game appeared in Persia under a new name  (shatranj  or  chatang)  and slightly revised rules.  It was possible to win in  shatranj  by capturing all pieces besides the King  (but it was a draw if the opponent could do the same on the next move).

The strongest  shatranj  player on record was  Al-Suli (AD 880-946)  the author of a famous  shatranj  problem known as  Al-suli's Diamond,  which was solved in by  Yuri Averbakh (1922-).  White wins by capturing the black ferz  which can only move diagonally one square at a time)  without losing his own on the next ply... in 19 moves!

The starting positions in those games were similar to that of chess  (up to a switch of the king and the minister/general/queen).  However,  the pieces had different names, shapes and properties  (somewhat shrouded in uncertainty)  as tabulated below. 

Pawns capture diagonally.  All other pieces capture the same way they move.
ChaturangaShatranjChessAllowed moves :
King  (Raja) King  (Shah) King One square,  laterally or diagonally.
Mantri Vizier / Ferz   One square,  only diagonally.
  Queen Any lateral or diagonal move.
Elephants   Jumps 1 or 2 steps,  diagonally.
  Bishops Diagonally.
Horses Knights Jumps 2 steps,  at 135° of each other.
Chariots   1 or 2 squares,  back,  forth or sideways.
  ChariotsRooks Laterally  (back, forth or sideways).
Padati Soldiers Pawns Forth 1 square  (diagonally to capture).
Elephants, horses and/or knights jump directly from origin to destination.  For other pieces,  a lateral or diagonal move is only allowed if intermediate squares are unoccupied.

At first,  the games were played on an  uncheckered  board of  64  squares  The familiar alternating light and dark colors of modern chessboards first appeared in Europe around 1090.

Some of the boards used were originally intended for an older  race game  called  ashtapada  (eight-legged)  whose exact rules seem lost.  16 special squares called  castles  were marked with crosses  (at the intersections of ranks 1, 4, 5 and 8 with files a, d,e and h).  Such marks are still found on some chessboards of Indian origin,  although their purpose is all but forgotten.


Legend has it that  Chaturanga  was invented for Iadava,  King of Telangana,  who was mourning the loss of his son Adjamir.  The Prince had died heroically to secure victory in a decisive battle at Decsina against the conqueror Varangul.

A young brahmin,  called  Lahur Sessa,  walked 30 days from the village of Manir to the  Andhra  royal palace and presented Iadava with the new game he had designed.  The king was so pleased that he asked the young man to name any reward he wished.  The lad made a simple request related to the 64 squares on the board:  He asked for one grain of wheat on the first square,  two on the second,  four on the third and twice as many grains on every square as on its predecessor.  The King thought that this was a modest price to pay,  until he was advised that the number of grains so named was humongous:

2 64 - 1   =   18446744073709551615
=   3 . 5 . 17 . 257 . 641 . 65537 . 6700417

Incidentally,  that factorization contains the five known Fermat primes and a famous factorization of Euler (1732):  232+1 = 641 . 6700417.)

Nice tale, isn't it?  Unfortunately,  that's all it is.  In  some versions,  the young inventor is made vizir for life.  In other versions,  he is executed.

Wheat and chessboard problem

By convention,  the chessboard is always oriented so that the closest corner to the  right  of either player is a  light  square  (light rhymes with right).  This was first specified in print by  Pedro Damiano (1480-1544)  in 1512.   Girolamo Cardano 
 1501-1576  The practice of shading  dark  squares in printed chess diagrams was introduced by  the famous scientist  Girolamo Cardano (1501-1576).

Three legal moves in modern chess have no equivalent in ancient games:

  1. On its first move,  a pawn may travel two squares forward  (if both the destination and the passed-over square are free).
  2. En passant capture  by a pawn is allowed  immediately after  one such move  (it takes place at the passed-over square).
  3. Castling  (French  roque;  14th or 15th century, in Europe)
    If all squares between the king and a rook are free,  then a legal move consists in moving the rook next to the king and having the king jump over it,  provided  the following conditions are met:
    • The king and the rook have never moved before.
    • No square in the  path of the king  is under attack.

In 1972,  the journalist  Tim Krabbé (1943-)  composed,  as a joke,  a  chess problem  whose solution involves a  vertical castling  on the "e" file using a rook created by pawn promotion which had never moved!  Krabbé even put forth the notation  O-O-O-O  for this hitherto unused third type of castling.  Shortly thereafter,  a new wording of the laws of chess was enacted to disallow that.

Chess used to be played until the king was actually captured.  This meant that a player who didn't move out of check  (or even moved into check)  would lose by having the king captured on the next turn,  unless the opponent blundered the game away.

To avoid such endings,  it was made illegal to move into check or not to mode out of check.  To make that modern rule easier to follow by weak players,  whoever puts a king in check must announce it.  In several languages,  the ploral form of such announcements morphed into the name of the game itself  (chess  is a corrupted form of  checks  in English;  the game is called  échecs  in French).

One interesting consequence of that modern rule is the possibility of  stalemate  (FrenchL  pat)  which is a situation when a player is not in check but has no legal move available.  This is now declared a  draw.  In some endgames,  the goal of the dominating player thus becomes to force  checkmate  while avoiding a stalemate situation.

Some obsolete rules even declared a  stalemate  to be a  win  for whoever was called to play from such a situation.  This was the case in England until 1800.

The German term  Zugzwang  (capitalized if German spelling is to be respected)  denotes a configuration which is less favorable if you have to move first than if you don't,  especially in endgame situations very near to a  checkmate  or  stalemate.  (In  combinatorial games theory  the term is sometimes used to denote a losing situation for whoever has to move first.)

The  oldest extant game  of modern chess was played in 1475 in  Valencia  between  Don Franci de Castellvi  (White)  and  Narciso Vinyoles  (Black).  The game illustrates a famous poem entitled  Scachs d'Amor  (Chess Game of Love)  written in Catalan  (more precisely  Valencian)  by  Castellvi  (Venus),  Vinyoles  (Mars)  and  Mossèn Bernat de Fenollar  (Mercury).

Chaturanga   |   Shatranj
Checkmate   |   Laws of Chess   |   Chess960 (1996)
History of Chess (7:05)  Wesley  (2014-10-09).
Cultural History of Chess (39:50)  Rick Knowlton  (AncientChess.com, 2014-06-30).

(2018-09-11)   Chess Tables,  Boards and Mats.
Various ways the actual chess playing surface is provided.

The generic term of  chessboard  (or just  board)  is used for all of these,  but it need not be an actual rigid board.  It can also be inlaid into a dedicated table or,  for best portability,  a mat can be used which can be folded or rolled up.

The most common size for tournaments has  2.25''  squares  (57 mm).  The playing surface itself is thus  18''  (46 cm).  Typically about  20''  with the borders which often feature two sets of rank numbers and file letters  (to accomodate both players).

Large boards are  22''  with  2.75''  squares.

 Come back later, we're
 still working on this one...

3 types of chess mats (1:54)  by  Wholesale Chess  (2012-08-03).
$450: The Stack Chess Board (9:02)  by  Raphael  (Chess House, 2016-01-19).

(2018-09-07)   Chessmen.
Recommended sizes.

When the game of chess is discussed abstractly,  we talked about pawns and pieces.  The word  chessmen  is normally used only for the physical objects made from wood, metal, stone, clay or plastic.

In modern tournament play,  only minor variants of the  Staunton  chessmen are used.  The official tournament guideline states that the base diameter of the king should be no more than 75% of the side of a squares on the chessboard.  Four pawns should barely fit into a square  (base diameter being 50% the side of a square).

Standard Dimensions of Staunton sets :
King Height2.5''2.75''3.15''3.54''3.9''4.5''
Square Side1''1.3''1.5''2''2.25''2.75''

 Come back later, we're
 still working on this one...

Some Variants of the Staunton Design :
StyleKingBaseMaterialWeighted2xQ(Best) ColorsPrice
Nero4.25''1.85''Polymer OKOK Dark & Light Brown $75
Hastings4.0''1.8375''Plastic OKOK Red & Natural $25
Marshall3.5''1.45''Silicone NoOK Black & White $17

Staunton chess set   |   Luxury chess sets  (2018)
Staunton designs (13:00)  by  Rick Knowlton  (AncientChess.com, 2011-03-15).
The Isle of Lewis Chessmen (9:52)  by  Rick Knowlton  (AncientChess.com, 2011-04-14).
The Lewis Chessmen (15:00, 14:12British Museum  (2013-11-11).
The Chamber of Lewis Chessmen (8:27)  by  Irving Finkel  (The British Museum, 2017-09-24).

(2018-08-07)   Chess Clock
Some controversial aspects of timed games.

Time limitations on chess games are of relatively recent origins.  Chess clocks have been used in competition since the London International Tournament of April 1883.

Time controls were born out of necessity to make the organization of tournaments possible.  The possibility of  losing on time  was originally just a way to enforce those time limits without altering the nature of the game.

Bonus and Delay :

Those are the two simplest ways to force fast play on low time without making it humanly impossible to execute decent moves.  In practice,  these two methods are  never  used together  (although they're not incompatible).

  • Bronstein delay  is also called  simple delay  or  US delay.  The player's alloted time doesn't start to be debited until a certain preset  delay  has ellapsed.  A player who plays  every  move faster than this preset delay will never run out of time.
  • Fischer increment  is a preset  bonus  time  which is added at the beginning of every turn.  The unused portion of those bonuses can accumulate so that a future move which requires more consideration can be played less recklessly.

Currently,  almost all  classical chess  tournaments endorsed by the  Worldwide Chess Federation  are played in 90 minutes  (per player)  for the first 40 moves and 20 minutes for each side for the rest of the game,  with a 30-second  Fischer increment  per move  (starting with the very first move).  That gives each player 110 minutes to complete the first 40 moves.  (That's code 04 on the  Wholesale Chess Advanced Digital Game Timer.)

For the World Championship  (and the qualifying Candidate Tournament)  the time limits are 100 minutes for the first 40 moves, 50 minutes for the next 20 moves and 15 minutes for the rest of the game.  Again with a 30-second Fischer increment starting at the first move.  (That's code 05 on the  Wholesale Chess Advanced Digital Game Timer.)

Japanese Byo-Yomi:

This is a more complicated time-control used for mostly for  shogi  and  go  but digital chess clocks often allow it.

 Come back later, we're
 still working on this one...

Gentleman's Rules:

It's a monstrosity to grant a win in chess to a player who doesn't even have enough pieces to mate  (although it's sometimes done in automated online play).  In that case,  a player is awarded a draw if the other runs out of time.

  • The game is an instant draw if neither player has enough to mate.
  • Furthermore,  a good  Gentleman's Agreement  in a timed game is to resign with a bare king if the other side has at least:
    • A queen.
    • A rook.
    • Two bishops.
    • A bishop and a knight.

It would be nice if chess-playing software enforced this automatically.

In over-the-board play,  someone who grabs a piece which has at least one legal move must play that piece  (the old-school  touch-move rule).  A legal move is final when the player lets go of the piece.  I argue that no penalty should be incurred when an illegal move is corrected before the clock is punched  (but punching the clock after an illegal move forfeits the game).

Time control   |   Chess Clock   |   Draw by agreement
ACP demands standardizing time controls in chess  (ChessBase, 2007-09-16).
Time Controls  (Chess.com, 2008-01-21).
Time Controls in the US  by  Greg Shahade  (USCF, 2012-09-21).
Tournament Life in the US   (Continental Chess Association).
Time control notation explained?  by  Derek Chiang  (Chess StackExchange, 2015-01-04).
How exactly do time controls work?  by  BradB132  (Reddit, 2015).
Carlsen loses because his opponent made an illegal move!  (7:12)   Antonio Radic  (Agadmator, 2017-12-29).
Advanced Digital Game Timer (17:08)  by  Wholesale Chess  (2017-07-07).

(2018-08-13)   Standard algebraic Notation   (Philipp Stamma,  1737)
Only one notation survives to record chess games,  with minor variants.

Each square is identified by a lowercase letter from "a" to "h" according to its file and a numeral from "1" to "8" according to its rank.  Squares are either  light  or  dark.  The corner squares to the right of either player  (h1 and a8)  are light.  In the starting position,  the white queen is on  d1  (a light square)  and the black queen is on  d8  (a dark square).  You may want to remember that queens start on their own colors.

Each type of piece  (besides the pawns)  is identified by a single capital letter:  K, Q, B, N, R  (at each move,  White  moves first and  Black  second).  When a piece is not specified,  a pawn move is understood  (the abbreviation  P  is deprecated).

In case of ambiguity  (when the landing square is accessible to two like pieces)  give the lowercase letter identifying the  file  (column)  where the piece is moving from  after  the name of the piece.  If that doesn't lift the ambiguity,  give the number of the  rank  instead.

Conceivably,  you might need to name the starting square fully,  by file and rank,  in the extremely rare case where the destination square is accessible to  three  like pieces at the corners of a rectangle.  Prerequisites for such a situation include a promotion to knight,  two queenings or two promotions to bishops!  Yet,  if you're a programmer,  you must anticipate such a weird thing.

  • Long  and short  castling  are respectively denoted  O-O-O  and  O-O.
  • When a pawn is promoted,  the piece it becomes is indicated after an equal sign  (formerly, a slash was used).  For example:   67.  c8=Q
  • No special notation is used  (or needed)  for  en passant  capture.
  • A move which puts the king in check is followed by a  plus sign  (+).
  • Checkmate is indicated by a  pound sign  #  (++ is deprecated).

In the computer era,  it's important to always record moves in the tersest way  (so plain text searches can fetch them).  However,  in handwritten or printed scores,  it's nice to name the captured piece for the sake of readability.  For example,  the key move in  Legal;'s mate  could be  written :

5.  Nxe5   BxQd1

Likewise,  one of five abbreviated  annotations  of one or two characters,  can be given after any move,  except  a checkmate or a forced move.

  • Brilliant  (!!).
  • Excellent  (!).
  • Debatable  (!?).
  • Dubious or inaccurate  (?!).
  • Mistake  (?).
  • Blunder  (??).

Unfortunatey,  the names of the pieces and their abbreviations are different in different languages  (in addition,  the French sometimes replace "c" and "e" by "ç" and "é").  For better international communication,  graphical hieroglyphs for the pieces are often used in print.

English K  Q  R  B  N  (P) 
German, Dutch, SwedishKDTLS(B)
  Italian, Spanish  RDTAC(P)
PortugueseBC( )
CzechKDVSJ( )

Other Notations :

Formerly,  both  the origin and destination were always recorded.  This convention is now fairly rare.  It's known as  long  or  reversible  because it makes it easy to move back from a position given in a diagram  (especially since the names of captured pieces are always given with the destination square).  For example:

1. e2-e4   e7-e5

Chess notation   |   Standard algebraic notation (SAN)   |   Descriptive notation (deprecated since 1981)
Foreign Names of Chess Pieces (ChessOps)

(2018-08-13)   The most common chess openings:
An advanced player's  repertoire  consists in familiarity with many lines.

White  has 20 possible first moves  (2 per pawn and 2 for each knight)  corresponding to the  20  headings below,  listed in order of popularity.  Because the  Sicilian Defense  (1. 1. e4 c4)  is so strong,  the second-most-popular opening move for White  (1. d4)  can be considered stronger than the most popular one  (1. e4)  whose continuations take up more space in this list than all the other variations combined.

This structured list introduces the  names  of some notorious openings discussed among players.  The  Oxford Companion to Chess  goes well beyond this,  with  1327  named opening lines.

1. King's Pawn Opening   1. e4
  • Sicilian Defense:
    1. e4 c5
    1. e4 c5 2. c3   Alapin Variation.
    1. e4 c5 2. Nf3 d6 3. d4 cxd4 4. Nxd4 Nf6 5. Nc3   Open Sicilian.
    1. e4 c5 2. Nf3 d6 3. d4 cxd4 4. Nxd4 Nf6 5. Nc3 a6   Najdorf.
    1. e4 c5 2. Nf3 d6 3. d4 cxd4 4. Nxd4 Nf6 5. Nc3 g6   Sicilian Dragon.
    1. e4 c5 2. Nf3 d6 3. d4 cxd4 4. Nxd4 Nf6 5. Nc3 e6   Scheveningen.
    1. e4 c5 2. Nf3 d6 3. d4 cxd4 4. Nxd4 Nf6 5. Nc3 Nc6 6. Bg5 e6   Richter-Rauzer.
    1. e4 c5 2. Nf3 d6 3. d4 cxd4 4. Nxd4 Nf6 5. Nc3 Nc6 6. Bc4 e6   Sozin.
    1. e4 c5 2. Nf3 d6 3. d4 cxd4 4. Nxd4 Nf6 5. Nc3 Nc6 6. Be2 e5   Boleslavsky.

    1. e4 c5 2. d4 cxd4 3. c3   Smith-Morra Gambit.
    1. e4 c5 2. d4 cxd4 3. c3 dxc3 4. Nxc3 Nc6 5. Nf3 e6
        6. Bc4 Qc7!? 7. Qe2 Nf6 8. O-O-O? Ng4! 9. h3??   Siberian Trap.
  • Caro Kann Defense:
    1. e4 c6
    1. e4 c6 2. d4 d5
    1. e4 c6 2. d4 d5 3. Nd2 dxe4 4. Nxe4 Bf5   Capablanca Variation.
        5. Ng3 Bg6 6. h4 h6 7. Nf3 Nd7 8.h5 Bh7   Spassky Variation.
    1. e4 c6 2. d4 d5 3. Nd2 dxe4 4. Nxe4 Ne7 5. Qe2!? Nf6?? 6. Nd6#    Cartoon
  • King Knight's Opening:
    1. e4 e5 2. Nf3
    1. e4 e5 2. Nf3 Nc6   Spanish / Italian / Scotch / Ponziani / 3-4 Knights ...
    1. e4 e5 2. Nf3 Nf6   Petrov Defense  (Russian Game).
    1. e4 e5 2. Nf3 Nf6 3. Nxe5 d6 4. Nxf7   Cochrane Gambit.
    1. e4 e5 2. Nf3 d6   Philidor Defense.
    1. e4 e5 2. Nf3 d5!? 3. exd5 Bd6   Elephant Gambit.
    1. e4 e5 2. Nf3 f5?!   Latvian GambitGreco Countergambit.
    1. e4 e5 2. Nf3 f6? 3. Nxe5!   Damiano Gambit.
  • Ruy Lopez  (Spanish game):
    1. e4 e5 2. Nf3 Nc6 3. Bb5
    1. e4 e5 2. Nf3 Nc6 3. Bb5 a6   Morphy defense.
    1. e4 e5 2. Nf3 Nc6 3. Bb5 a6 4. Ba4 Nf6
        5. 0-0 Be7 6. Re1 b5 7. Bb3 0-0 8. c3 d5   Marshall Attack   [video]
    1. e4 e5 2. Nf3 Nc6 3. Bb5 Bc5 4. c3  Classical defense.
    1. e4 e5 2. Nf3 Nc6 3. Bb5 Bc5 4. c3 Nf6   Benelux.
    1. e4 e5 2. Nf3 Nc6 3. Bb5 Bc5 4. c3 f5   Cordel gambit.
    1. e4 e5 2. Nf3 Nc6 3. Bb5 Bc5 4. c3 Bb6   Charousek.
    1. e4 e5 2. Nf3 Nc6 3. Bb5 Bc5 4. c3 Qe7   Boden.
    1. e4 e5 2. Nf3 Nc6 3. Bb5 Bc5 4. O-O   Zaitsev.
    1. e4 e5 2. Nf3 Nc6 3. Bb5 Bc5 4. Bxc6? dxc6 5. Nxe5 Qd4
    1. e4 e5 2. Nf3 Nc6 3. Bb5 Nf6   Berlin Defense.
    1. e4 e5 2. Nf3 Nc6 3. Bb5 Nf6 4. O-O Nxe4 5. d4 Nd6 6. Bxc6!?
        6. ... bxc6 7. dxe5 Nb7 8. Nc3 Be7 9. Bf4 O-O 10. Re1   Lasker.
        6. ... dxc6 7. dxe5 Nf5
    1. e4 e5 2. Nf3 Nc6 3. Bb5 Nf6 4. O-O Ng4!?
        5. h3? h5! 6. hxg4?? hxg4   Fishing Pole  trap.
  • Italian game  (Greco, 1620):
    1. e4 e5 2. Nf3 Nc6 3. Bc4
    1. e4 e5 2. Nf3 Nc6 3. Bc4 Nf6   Two-Knights Defense.
    1. e4 e5 2. Nf3 Nc6 3. Bc4 Nf6 4. Ng5   Fried-Liver Attack.
    1. e4 e5 2. Nf3 Nc6 3. Bc4 Nf6 4. Ng5 d5 5. exd5
    1. e4 e5 2. Nf3 Nc6 3. Bc4 Nf6 4. Ng5 Bc5!? 5. Nxf7? Bf2+   Traxler.
    1. e4 e5 2. Nf3 Nc6 3. Bc4 Nf6 4. Ng5 Bc5!? 5. Bxf7+ Ke7   Wilkes-Barre.
    1. e4 e5 2. Nf3 Nc6 3. Bc4 Be7   Hungarian Defense.
    1. e4 e5 2. Nf3 Nc6 3. Bc4 Bc5 4. c3   Giuoco Piano.
    1. e4 e5 2. Nf3 Nc6 3. Bc4 Bc5 4. d3   Giuoco Pianissimo.
    1. e4 e5 2. Nf3 Nc6 3. Bc4 Bc5 4. b4   Evans Gambit.  [ Young Morphy ]
    1. e4 e5 2. Nf3 Nc6 3. Bc4 Bc5 4. Ng5   [ Fried-Liver Attack ]
  • Scotch Game  (del Rio, 1750.  Edinburgh-London, 1824):
    1. e4 e5 2. Nf3 Nc6 3. d4
  • Ponziani Opening:   [ video ]
    1. e4 e5 2. Nf3 Nc6 3. c3
    1. e4 e5 2. Nf3 Nc6 3. c3 Nf6!   Jaenisch Variation
    1. e4 e5 2. Nf3 Nc6 3. c3 d5
    1. e4 e5 2. Nf3 Nc6 3. c3 f5!?   Ponziani's countergambit  (1769).
  • Three-Knights Game :
    1. e4 e5 2. Nf3 Nc6 3. Nc3   [ traps ]
    1. e4 e5 2. Nf3 Nc6 3. Nc3 Nf6   Four Knights Defense.
    1. e4 e5 2. Nf3 Nc6 3. Nc3 Nf6 4. d4   Scotch Variation.  C47
    1. e4 e5 2. Nf3 Nc6 3. Nc3 Nf6 4. d4 Bb4 5. Nxe5   Krause Gambit.
    1. e4 e5 2. Nf3 Nc6 3. Nc3 Nf6 4. d4 exd4 5. Nxd4   Scotch main line.
    1. e4 e5 2. Nf3 Nc6 3. Nc3 Nf6 4. d4 exd4 5. Nd5!?   Belgrade Gambit.
    1. e4 e5 2. Nf3 Nc6 3. Nc3 Nf6 4. Nxe5 Nxe5 5. d4   Halloween Gambit.
  • Vienna Game :
    1. e4 e5 2. Nc3
  • Center Game :
    1. e4 e5 2. d4 exd4 3. Qd4 Nc6
  • Danish Gambit  {Severin From, 1867} :
    1. e4 e5 2. d4 exd4 3. c3
  • Bishop's Opening:
    1. e4 e5 2. Bc4
    1. e4 e5 2. Bc4 f5?!   Calabrese Countergambit.
    1. e4 e5 2. Bc4 Nf6 3. d4 exd4 4. Nf3   Urosov gambit (49:45).
  • Scholar's Attack :
    1. e4 e5 2. Qh5   Wayward Queen Attack.
    1. e4 e5 2. Qh5 Nc6 3. Bc4 g6 4. Qf3 Nf6 5. ... Nd4!
    1. e4 e5 2. Qf3?!   Napoléon Opening.
  • Alapin's Opening:
    1. e4 e5 2. Ne2
  • French Defense:
    1. e4 e6
    1. e4 e6 2. d4 d5 3. e5   Advance Variation.
    1. e4 e6 2. d4 d5 3. Nc3 Bb4 4. e5 c5 5. a3 Bxc3+ 6. bxc3   Winawer
    1. e4 e6 2. Nf3 d5 3. Nc3 ...
  • Nimzowitsch Defense:
    1. e4 Nc6
  • Scandinavian Defense:
    1. e4 d5 2. exd5
    1. e4 d5 2. Nf3 dxe4 3. Ng5   Tennison Gambit.
    1. e4 d5 2. Nf3 dxe4 3. Ng5 Nf6 4. d3 exd3? 5. Bxe3 h6?
        6. Nf7! Kxf7 7. Bg6+ Kxg6 8. Qxd8   Queen for Knight and Bishop.
  • Pirc Defense (pronounced peerts).  Yugoslav defense.
    1. e4 d6
    1. e4 d6 2.d4 Nf6 3.Nc3 g6 4.f4 Bg7 5.Nf3   Austrian Attack
  • Owen's Defense  (Greek Defense).
    1. e4 b6
  • King's Gambit:
    1. e4 e5 2. f4
    1. e4 e5 2. f4 exf4   King's gambit accepted  (KGA).
    1. e4 e5 2. f4 exf4 3. Bc4   Bishop's Gambit.
    1. e4 e5 2. f4 exf4 3. Bc4 Qh4+ 4. Kf1   Immortal Opening.
    1. e4 e5 2. f4 exf4 3. Nf3 g5 4. Bc4 g4 5. O-O gxf3 6. Qxf3   Muzio Gambit.
    1. e4 e5 2. f4 d5   KGD;  Falkbeer Countergambit
    1. e4 e5 2. f4 f5?!   KGD;  Panteldakis Countergambit (Greco, 1625)
    1. e4 e5 2. f4 Bc5   King's gambit declined; classical defense.
    1. e4 e5 2. f4 Bc5 3. fxe5?? Qh4+   (Novice trap.)
  • Alekhine's Defense.
    1. e4 Nf6
    1. e4 Nf6 3. d3
    1. e4 Nf6 3. Nc3
    1. e4 Nf6 2. e5! Nd5 3. d4 Nb6 4. Nf3?! dxe5 5. Nxe5 c6!
    1. e4 Nf6 2. e5! Nd5 3. d4 Nb6 4. d5 Nd5   Lasker Attack.
  • Modern Defense  (Robatsch).
    1. e4 g6 2. d4
  • Adams Defense   1. e4 Nh6   Wild Bull, Hippopotamus.
  • Barnes Defense   1. e4 f6
2. Queen's Pawn Opening   1. d4   (A40) 3. Zukertort Opening   1. Nf3 4. English Opening   1. c4
  • 1. c4 e5   Reverse Sicilian
  • 1. c4 e6   Agincourt Defense
  • 1. c4 c5   Symmetrical Defense
    1. c4 c5 2. Nf3 Nc6 3. Nc3   Two-Knight Variation.  (Tal-Anand,  Feb. 1989).
5. King's Fianchetto Opening   1. g3  (Benko's Opening)
  • 1. g3 ... 2. Bg2
6. Bird's Opening   1. f4
  • 1. f4
7. Queen's Fianchetto Opening   1. b3  (Larsen's Opening)
  • 1. b3
8. Baltic Opening   1. Nc3   HeinrichsenDunst, etc.
  • 1. Nc3 d5
  • 1. Nc3 c5
  • 1. Nc3 Nf6
  • 1. Nc3 e5!?
9. Polish Opening   1. b4   (Sokolsky, 1963)  Orangutan.
  • 1. b4 e5   Standard.
  • 1. b4 b6   Symmetrical.
  • 1. b4 e6
10. Van't Kruijs Opening   1. e3!?
  • 1. e3 e5 2. Qh5 Nc6 3. Bb5
11. Grob's Attack   1. g4
  • 1. g4 d5 2. Bg2 c6  
  • 1. g4 e5 2. e3  
12. Mieses Opening   1. d3
13. Anderssen's Opening   1. a3   (Anderssen-Morphy, 1858).
14. Saragossa Opening   1. c3   (Zaragoza, Spain), 1919).
15. Clemenz Opening   1. h3
16. Barnes Opening   1. f3
17. Ware Opening   1. a4   Meadow Hay Opening.
18. Desprez Opening   1. h4
19. Durkin Opening   1. Na3   (Sodium Attack).
20. Amar Opening   1. Nh3   (Ammonia Opening).  Yes,  it stinks!    Cartoon
  • 1. Nh3 e5 2. f3 d5 3. Nf2.   Krazy Kat.
  • 1. Nh3 d5 2. g3 e5 3. f4?! Bxh3 4. Bxh3 exf4   Paris Gambit.

A given situation can often be obtained by executing the same moves in different orders.  In that case,  the resulting variations are said to be  transposed  from each other.  For example,  the  Nf3  variation of the Scandinavian defense transposes to a Zukertort opening:

1. e5 d5 2. Nf3       -->       1. Nf3 d5 2. e5

All Chess Openings by First Move   |   Transposition   |   Transposition tables  (dynamic programming)
List of chess openings   |   Irregular chess openings   |   Hypermodernism   |   Schools of Chess
Chess openings  &  Study plan  (Chess.com).
Top 10 Chess Openings of Garry Kasparov  by  Yury Markushin  (TheChessWorld, 2017-01-13).
First moves in chess databases:   365Chess.com   |   ChessGames.com
Top 7 Aggressive Chess Openings (9:38)  by  Kevin Butler  (TheChessWebsite, 2014-09-03).
Harry Nelson Pillsbury (1872-1906):  The man who invented  1. d4  (10:16)  Agadmator   (2017-09-01).

(2018-09-02)   Combinatorics of Chess

Number of possible chess configurations after  n  plies.
n01234567 OEIS
Diagrams120400536271852815677926061094305342 A019319
Positions120400536272078822518941768196400068 A083276

chess diagram  merely describes the positions of the various pieces on the chessboard.  whereas a  chess position  also includes information about  castling  and  en passant  priviledges.  (The terms  configuration  or  situation  are used here to cover either concept indifferently.)

The two enumerations start to differ after two full moves  (four plies)  when a white pawn is on rank  5  with a black pawn to its immediate right or left  (and any other black move played elsewhere).  In this case,  White has  en passant  priviledges for the third move  only when  that side pawn arrived there on the  second  black move.

complete position  consists of a  chess position  and a  ply number  (odd only when it's White's turn to play).  Transposition tables  in chess-playing software typically contain only positions with ply-parity  (indicating whose term it is to play)  although complete ply information would be needed to properly deal with draws by repetition and apply the  50-move rule  (and/or the new  automatic  75-move rule,  officially introduced in 2014).

In the case of the above enumeration,  the ply number is given  a priori,  so the mere  position  fully determines the  complete position.

Numericana :   Combinatorics

(2018-08-24)   Systems:  Formations involving several pieces.
Opening systems may be valuable even if incompletely executed.

All systems are difficult to classify in standard books of openings because,  by definition,  they are routinely  transposed  into several lines.

  • London system.
  • Stonewall system.
  • Colle system.
  • Tartakower-Makogonov-Bondarevsky System  (TMB).
  • Hedgehog system.

 Come back later, we're
 still working on this one...

(2018-08-15)   Maxims and Aphorisms
A tiny collection of chess proverbs and famous quotes.

  • If you see a good move, try to find a better one.  (Damiano, 1512)
  • Knight on the rim is grim.
  • A pawn on the seventh is worth two on the fifth.
  • Brilliancy can only occur if the opponent makes a mistake.  (Rubinstein)

(2007-07-01)   Endgames and Nalimov Tables
Tabulating all positions is an efficient way to solve an endgame perfectly.
 Mate with Bishop
 and Knight 

If the total number of game positions is small enough, then each of them can be allotted a small computer record in an explicit table.  The entire game can then be solved efficiently by analyzing that table  top-down  (first completing the records corresponding to final positions, like checkmates).  For the game of chess, this is practical only in endgame situations, when only very few pieces remain on the board.

database  is a set of stored key/value pairs, where only a small portions of the possible keys exist  (for example, not all possible surnames exist in a database of people whose names are used as "keys").  By contrast, a  tablebase  includes (almost)  all  keys.  The key itself need not be stored in a tablebase; it's merely used to compute the unique numerical address where the information corresponding to that key is located.  In game tablebases, the game position is the "key" used to access the value recorded in the tablebase.

By contrast, in a data base, only a tentative address can be computed, based on a so-called  hash-code  which a key may share with many other possible keys.  The location computed from the key's hash-code is merely a starting point where a whole list of keys can be found (with their associated recorded values).  When a database is queried for a key, the query key must be compared with the stored keys.  The size of a database containing n different keys is thus more than  n lg n  bits.  (A tablebase which associates a single bit to each of n possible keys has a size of only  n bits.)

Perfect play  is defined as achieving victory as fast as possible, or delaying defeat as much as possible.  A full analysis of the game is normally possible only by recording the length of a perfect game for each tabulated position  (the position is a first-player win when that length is odd, it's a first-player loss otherwise  (the issue of ties is discussed below).

A computer database which gives the number of half-moves to the end of a perfectly played game is called a  Nalimov table.  It's easy to play perfectly by looking up such a table:  Play into the smallest even position if you can, otherwise play into the largest odd position.  A special label must be assigned to ties which is adequately defined as an odd number larger than any other...  (for example 255, if Nalimov records consist of a single byte).

There is no notion of "perfect play" for a game which ends in a tie.  Such a game is merely considered equivalent to a game which goes on forever because neither player can force a victory.  Yet, it's possible to refine Nalimov values to distinguish between a tie  "by the book"  (which tells that an undecided game is over) having the highest odd value and other ties which have odd values just below that  (but above any other odd values corresponding to true first-player wins).

Error-free play  (as opposed to perfect play)  can be defined as what happens when neither player gives up victory when it's available to them.  It is not required of the winner to force a quick conclusion.  A practical "tie" may even result if victory is postponed indefinitely  (a win may thus be transformed into a tie by the actual rules of chess which limit the number of capture-free moves).
Compact bit-wide tablebases, known as  bitbases,  are sometimes used in actual chess-playing programs as "oracles" which help make error-free decisions in the endgame.  A  single bit  is assigned to each position whose value is zero (0) if and only if it is a first-player loss.  The value "1" corresponds to a first player win if and only if it has at least one option labeled "0"  (otherwise, the "1" indicates a tie).
A bitbase  (for mere error-free play)  is normally obtained by extracting the relevant information from a complete Nalimov table.

Eugene Nalimov  was born in Novosibirsk in 1965.  He joined Microsoft as a programmer in 1997,  he later joined the Seattle-based  Context Relevant  startup  (called  Versive  since 2017).  Nalimov started writing tablebases generators for chess endgames in 1998.  He was honored for that work by  ChessBase  at their 2002 convention,  in  Maastricht.

Example: The Knight and Bishop Endgame

The basic table base (TB) only needs to consider the positions where the bishop is on one of the 16 topmost white squares.  Ignoring obvious illegal positions (e.g., several pieces on the same square or adjacent kings) the other pieces can be on one of 64 squares and it can be the turn of either Black or White.  All told, the size of the TB, at one byte per position, is fairly small:

2 . 16 . 64 . 64 . 64   =   8 MB

Each of those bytes contains the number of moves to mate.

Endgame Tablebase   |   Just one of 17,823,400,766 positions  (Chess News,  2002-01-04).
Checkmate with two bishops (6:22)  by  Jeetendra Advani  (Chess Talk, 2017-12-02).

(2010-01-28)   Static Evaluation Function
Evaluating quiescent positions is an art form.

 Come back later, we're
 still working on this one...

QueenRookBishopKnight PawnBishop pairAuthors
1031Philidor 1777
9531Fisher 1972
9331Kasparov 1986
8.805.103.333.201Berliner 1999

Relative value of chess pieces   |   Evaluation function   |   Compensation   |   Hans Berliner (1929-2017)

(2010-01-28)   Minimax Search
Minimize your opponent's gain, maximize your own.

 Come back later, we're
 still working on this one...

(2010-01-28)   Alpha-Beta Pruning
In a minimax search, some alternatives need not be explored at all.

 Come back later, we're
 still working on this one...

(2010-01-28)   Hash Tables
How to avoid exploring the same position more than once.

 Come back later, we're
 still working on this one...

 One of 4 possible positions 
 at the end of a 2-move game.  (2010-01-27)   Short Games
Checkmates in the opening moves.

1.  Fool's mate  (2-move mate) :

This is the shortest of all chessgames.

There are  8  variations which result in a position similar to the one depicted at right, where White is checkmated.  They differ by the order White moves his two pawns and also by two possible choices for moving the central pawns of each player  (one square or two squares).

The locution  fool's mate  is sometimes used as a generic term to denote any  very early checkmate, especially the following one:

 How Mikhail Tal (Black) got defeated, 
 at age 9 by his brother (White).  Riga, 1945.  

2.  Scholar's mate (Queen raid)

At age 9, Tal, lost to his brother thusly:

1. e4   e5     3. Qh5  Na6
2. Bc4  Bc5    4. Qxf7#

This mate is often attempted among newcomers.  The French call it  le coup du berger  which translates literally as  Shepherd's mate, as do the names of that checkmate in several other languages, including Spanish, German, Dutch and Portuguese.

The  fool's mate  and  scholar's mate  may well be as old as chess itself but they were apparently not mentioned in print before the seventeenth century, as they found their rightful place in the early classification proposed by one  Arthur Saul  in  "Famous Games of Chesse-play" (1614).

Counting the number of 4-move games ending in a  scholar's mate  can be an interesting exercise:  The game may end with  Qf3xf7#  (e.g., after the infamous Napoléon opening)  or  Qh5xf7#  (as above).  In either case, White can play in 4 different ways  (opening with either e3 or e4, then moving either the bishop or the queen).  Each sequence makes different "compatible" moves available to Black.  If the black queen moves, she must move back.  To allow the mating move, the white queen's path must be clear and  f7  must be unprotected...

How to beat the four-move checkmate (4:36)  by  ChessVision.net  (2008-01-28).
1. e4 e5 2. Qh5 Nc6 3. Bc4 g6 4. Qf3 Nf6 5. ... Nd4

(2018-08-27)   Fried-Liver Attack
Played sharply,  the super-agressive  Traxler counter-attack  can pay off!

Most beginners are exposed to the elementary  fried-liver attack  shortly after learning about the the above  Scholar's mate.  The  usual defense  is:

1. e4 e5 2. Nf3 Nc6 3. Bc4 Nf6 4. Ng5!? d5

However,  the following analyzed game illustrates a  bold  counterattack which is far from elementary  (to avoid it,  White could play  5. Bxf7+  gaining a pawn).  If White  ever  loses a tempo with  Nxh8  then the game is hopelessly lost when Black plays perfectly!  I'm using this as an example of how a written analysis can be presented:  We show the strongest move of the winning side  (Black here)  for  every  possible reply of the opponent,  except  when the move to be refuted  (Nxh8)  is played.

The paradoxical consequence of the following refutation of  Nxh8  is that the threat on the rook is only  apparent.  At least for  extremely  sharp play...

Conveniently,  the quoted 1967 game doesn't last very long because of the mistakes of White  (starting with  6. Kxf2).  The opponent of Traxler in 1890 didn't take the bait,  which opens up an interesting 17-move game.  Both actual games are  shown in bold,  within the combined  decision tree.

F. Hollingsworth vs. Ron Steensland      [ WARNING: Hand analysis.
(68th US Open, Atlanta, Auguat 1967)                Not finalized. ]

1. e4 e5 2. Nf3 Nc6 3. Bc4 Nf6 4. Ng5! Bc5! 5. Nxf7!? Bxf2+
   6. Kxf2? Nxe4+
      7. Ke3? Qh4 8. Nxh8?? Qf4+
         9. Kd3 Nb4+ 10. Ke2 Qf2#
         9. Ke2 Qf2+ 10. Kd3 Nc5+! 11. Kc3 Qd4#
      7. Kf3? Qh4 8. Nxh8? Nd4+
  [or 7. Ke2? Qh4 8. Nxh8? Nd4+ (9. Kf1?? Qf2#)] 
         9. Ke3 Qf4+ 10. Kd3 {A: Mate in 7} Nc5+!! 11. Kc3 Nb5+!
            12. Bxb5?? Qd4#
            12. Kb4  a5+!!
                13. Kxc5? Qd4+ 14. Kxb5 Qb6+ 15. Ka4 Qb4# 
                13. Kxb5 b6!
                    14. ... Ba6#
                    14. Qh5+! Ke7 
                        15. Qh4+ Qxh4 16. ... Ba6#
                        15. Qg5+ Qxg5 16. ... Ba6#
         9. Kd3 Nc5+
            10. Ke3? Qf4#
            10. Kc3 Na4+
                11. Kb4 Qe7+!
                    12. a5? Qc5+ 13. Kxa4 Qxc4+
                        14. Ka3 Nb5#
                        14. Ka5 Nc6#
                    12. Kxa4 a5!!
                        13. ... Qb4#
                        13. a3/c3 d4!
                            14. ... Bd7!
                11. Kd2 ...
      7. Ke1 Qh4+ 8. g3 Nxg3 9. hxg3 Qxg3+ 10. Kf1 Rf8 (or O-O)
      7. Kg1 Qh4 8. g3 Nxg3 9. hxg3 Qxg3+ 10. Kf1 Rf8 (or O-O)
      7. Kf1! Qf6+ (8. ... Qf2#) 8. Qf3! Qxf7 9. Kxf7 Rf8 (or O-O)

J. Reinish vs. Karel Traxler
(Hostoun near Prague, 20 March 1890)

   6. Ke2?  Nd4+! 
      7. Kd3? b5!
         8. Bb3 Nxe4!!                     (Queen sacrifice)
            9. Nxd8? Nc5+ 10. Kc3 Ne2+!    (Knight sacrifice)
               11. Qxe2 Bd4+ 12. Kb4 a5+
                   13. Kxb5 Ba6+ 14. Kxa5 Bd3+ 15. Kb4 Na6+
                       16. Ka4 Nb4+ 17. Kxb4 c5#
                       16. Ka5 Nb4+ 17. Kxb4 c5#
                       16. Ka3 Nb4+ 17. Kxb4 c5#
                   13. Ka3?? b4#
               11. Kb4? a5+ (Same ending, one move sooner.)
            9. ...
         8. ...
      7. Kxf2? Nxe4+
         8. Ke3 Qh4 9. Nxh8? Qf3+ 10. Kd3 {A: Mate in 7, above.}
         8. Kf1 Qf6+ (9. ... Qf2#) 9. Qf3! Nxf3
            10. gxf3 Qxf3+ 11. ... Qf2#
            10. Ke2 Nd4+ 
                11. Ke1 Qf2#
                11. Ke3 (or Kc3) Qf3#
            10. ... Nd4 11. ... Qf2#
         8. Ke1
      7. Kf1! Qe7 7. Nxh8? d5
         8. exd5 Nd4  (Recommended by Karel Traxler himself.)
            9. ...
         8. Bxd5 Nxd5
            9. exd5 Bg4+!?
               10. Kxf2? Qf6+
                   11. Kg3?? Qf4#
                   11. Kg1? Bxe1 12. ... Nd2#
                   11. Ke3 Qf3+ 12.Kd3 Be2+
                       13. Kc3 Nb5+ 14. 
                       13. Qxe2 Qxe2+ 14. Kc3 Nb5+ 15. Kc2 Bc4+
                           16. Ka4 Bxe5+
                               17. Ka3 
                               17. Kxb5 Qc4+ 18. a5 Qc5+ 19. Ka4 b5+
                                   20. Kb3 Qc4+ 21. Ka3 Qa4#
                                   20. Ka5 b4+ 21. Ka6 Qb6# 
                   11. Ke1 Bxd1
                       12. Kxd1 Qf2
                           13. ... Qd2#
                           13. Rd1 Qxg2
                               14. Rf1?? Qd2#
                               14. ... Qf3+ 15. Rd2 Qxd2#
                       12. ... Qd2#
                       12. Rf1! Qa6! (13. ... Qd2#)
                           13. Rf2!? O-O ...
                           13. d3 Qa4!
                               14. b2 Nxb2
                                   15. axb2 Qxa1
                                       16. Kxd1 Qxa1
                                       16. ...
                               14. Ke1 Nc2+
                                   15. Kf2 Qf4#
                                   15. Kg1 Qg4 ...
               10. ...
            9. ...
         8. ...
   6. Kf1! Qe7
      7. Nxh8? d5
         8. exd5 ...
         8. ...
      7. Ng5!? ...
      7. ...

The term  Traxler counterattack  is normally used to describe this opening  (especially when the Bishop's sacrifice is accepted,  as in Traxler's original game  6. Kxf2).  However,  in the United States,  it's also called the  Wilkes-Barre Variation  (especially when  6. Ke2  or  6. Kf1  is played)  because it was analyzed by  John Menovsky (1873-1947)  and other members of the  Wilkes-Barre Chess Club  (first established in 1887 and restarted in 1907).  Menovsky published the work in 1934 and 1935 and subsequently discussed the problem with  Kenneth F. Williams (1907-1993)  who would eventually published a 58-page pamphlet on the topic in 1979  (still somewhat flawed).  Williams was once President of the  Correspondence Chess League of America (created in 1909).

Even with the best reply  6. Kf1  White lost  all  the games on record:

  • 1950:  Lichy vs. Frantisek Blatny  (10 moves).
  • 1955:  Kerner vs. Alfred Brinckmann  (15 moves).
  • 1958:  Cosling vs. Peter Murray  (13 moves).
  • 1959:  Rosenbaum vs. Norman J. Goldberg  (18 moves).
  • 1964:  Julio Kaplan vs. Canoromi  (19 moves).
  • 1964:  Julio Kaplan vs. Canoromi  (16 moves).
  • 1964:  Babitsky vs. Georgy Sapundzhiev  (15 moves).
  • 1964:  Grebenshikov vs. Grigoriev  (22 moves).
  • 1965:  Yakov Estrin vs. Jiri Nun  (16 moves).
  • 1966:  V. Sarkisian vs. Alekper Shahtahtinsky  (18 moves).
  • 1966:  S. Kurkin vs. Yakov Estrin  (25 moves).
  • 1966:  Lueck vs. Endres  (25 moves).
  • 1967:  Wead vs. P. Larsson  (13 moves).
  • 1971:  Tarakanov vs. Solomon Naftalin  (19 moves).
  • 1971:  Siegfried Augustat vs. K. Hentzgen  (19 moves).
  • 1974:  Lothar Schmid vs. Helmuth Lietz  (13 moves).
  • 1974:  M. Sedayao vs. G. Boyd  (13 moves).
  • 1982:  Roger Pernet vs. Colin A. Costello  (17 moves).
  • 1987:  N. Lipowsky vs. Richard Forster  (15 moves).
  • 1989:  Reinhard Fiedler vs. Lothar Simchen  (16 moves).
  • 2001:  Huang Yicheng vs. Zhang Yuntao  (26 moves).  Timeout?

They  all  lost a tempo with  Nxh8,  cornering the knight.

The Opening Boomerang  by  GM  Gregory Serper  (Chess.com, 2016-02-14).
The Traxler Counter Attack  by  Sarah Beth  (Chess.com, 2015-06-13).
CN 9334  by  Edward Winter  (2015-06-16).
Zlatá Praha  (1892-10-14).
Grandmaster/supercomputer looks at Wilkes-Barre  by  Richard Moody, Jr.  (Chess.com, 2013-07-20).
Crushing Counter-Attack against Fried-Liver Attack (4:07)  by  Mato Jelic  (2011-04-04).
Fried Liver Attack (10:58)  by  Kevin Butler  (TheChessWebsite, 2010-05-23).
Traxler Counter-Attack (20:27)  by  Kevin Butler  (TheChessWebsite, 2010-11-20).

(2018-08-21)   Miniature Games
Checkmate in  24  moves or less.

All miniature games last less than  30  moves.  Some will only consider shorter games.  I define a miniature as a game two dozen moves or less,  which accomodates nicely the  fabulous  game discussed first.

The Immortal Game  (1851) :

Arguably,  the most famost miniatures of all time was played informally on 21 June 1851,  during a recess of the  first international chess ournament,  between  Adolf Anderssen (1818-1879)  and  Lionel Kieseritzky (1806-1853).  Anderssen,  playing White,  sacrificed his queen,  two rooks and a bishop to deliver a brilliant mate with the three remaining minor pieces  (without capturing a single black piece).

1. e4 e5 2. f4 exf4 3. Bc4 Qh4+ 4. Kf1 b5? 5. Bxb5 Nf6
6. Nf3 Qh6 7. d3 Nh5 8. Nh4 Qg5 9. Nf5 c6 10. g4! Nf6
11. Rg1 cxb5? 12. h4 Qg6 13. h5 Qg5 14. Qf3 Ng8 15. Bxf4 Qf6
16. Nc3 Bc5 17. Nd5 Qxb2 18. Bd6 Bxg1 19. e5!! Qxa1+
20. Ke2 Na6 21. Nxg7+ Kd8 22. Qf6+!! Nxf6 (23. Be7#)

Réti's Mate  (Vienna, 1910) :

Richard Réti (1889-1929)  against  Savielly Tartakower (1887-1956):

1. e4 c6 2. d4 d5 3. Nc3 dxe4 4. Nxe4 Nf6 5. Qd3 e5?
6. dxe5 Qa5+ 7. Bd2 Qxe5 8. O-O-O Nxe4? 9. Qd8+!! Kxd8
10. Bg5+ Kc7 11. Bd8# (or 10. ... Ke8 11. Rd8#)

The Original Immortal Game (7:11)  by  Antonio Radic  (Agadmator, 2017-09-01).
Homer Simpson vs. Marge Simpson (3:41)  by  Antonio Radic  (Agadmator, 2017-09-01).
Game of the Century:  Bobby Fischer vs. Donald Byrne (24:52)  by  Kevin Butler  (TheChessWebsite, 2010-07-18).
Short Chess Games by Serguei Vorojtsov:   | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 |

(2010-01-29)   Sam Loyd's Chess Puzzles
Toying with chess positions which can't arise in actual games.

The American columnist  Sam Loyd (1841-1911)  devised many clever puzzles based on the rules of chess which have no relevance to actual play.

Lone black king on h4  (against 16 white pieces).  Mate in 3 moves.  The same problem for other positions for the black king is less easy to analyze.  Tabulated below are the number of moves needed to mate, according to  Fritz 8.  In this context,  e4  is almost always the strongest move; often the  only  strongest move, as indicated by the exclamation mark (!)...  d4  is second best.

Full White Starting Lineup against Lone Black King
abcd efgh
 8  e4! (#8)e4! (#8)e4! (#9)d4! (#9) e4! (#9)e4! (#9)e4! (#8)e4! (#7)
 7  abcd efgh
 6  abcd ee4! (#9)gh
 5  abce4 (#10) e4! (#9)fgh
 4  e4 (#6)e4! (#8)e4! (#7)e4! (#8) d4! (#9)d4 (#9)e4! (#6)d4! (#3)

The Excelsior Problem  (1861).  Mating with the least likely piece.

(2010-01-28)   Opening Traps
Well-known deadly traps in the opening game.

Ruy Lopez, Berlin defense; The "fishing pole" black trap  (1, 2, 3, 4)

Trap in the Trompowsky attack

Ryder Gambit (Halosar trap).

Stafford Gambit.

Tennison Gambit.

Lasker Trap.

 Come back later, we're
 still working on this one...

700 Opening Traps  by  Bill Wall  (2010).
7 Best Chess Opening Traps (18:28)  by  GM  Igor Smirnov  (Remote Chess Academy, 2017-12-27).
5 Best Traps in the Italian Game (43:53)  by  GM  Nadya Kosintseva  (iChess.net, 2017-10-03).
10 Fastest Chess Opening Traps (32:07)  by  FM  Sebastian Fell  (iChess.net, 2017-08-04).
10 Deadliest Chess Opening Traps (18:37)  by  Yury Markushin  (Chess Channel, 2017-04-10).
Bobby Fischer's 3 Best Chess Traps ()  by  IM  Valeri Lilov  (iChess.net, 2017-10-20).

(2018-08-09)   Elo Rating System
Rating player skills in a zero-sum game.

 Come back later, we're
 still working on this one...

Comparing ratings from different eras :

Actual Elo evaluations allow the average of top players to drift substantially over time and the individual ratings are subject to considerable uncertainty.

The skills of individual players throughout history is best estimated by analyzing a significant sample of the individual moves they actually played in the midgame  without  significant time constraints.

The opening moves should not be examined,  as those depend greatly on current fashion and/or collective encyclopedic knowledge which evolves over time.  Bobby Fisher tried to eliminate that by introducing what's now called Chess960,  where the starting position is randomized among 960 possibilities.

One weakness of this approach is that the current  chess engines  outplay the best human players using an artificial style which is a poor predictor of typical human opposition on a move-by-move basis.  Yet,  the results so obtained are equally flawed throughout history and give an objective evaluation of actual skills which strongly correlates with performance in actual matches between humans.

Computerization also allows private estimates of the Elo rating of players who don't participate in regular chess tournaments with FIDE-rated players.

Elo rating system   |   Arpad Elo (1903-1992)   |   Chessmetrics   |   Jeff Sonas
Comparing top chess players in History

(2018-08-17)   Odds Chess.  Handicapping a single game of chess.
The traditional way to even out a game between players of different strengths.

In a game  at odds of pawn and 2  (P and 2)  the stronger player plays the black pieces without the  f7  pawn and  White  plays two initial moves.

With  rook odds,  White plays without the  a1  rook.  The  "a"  pawn is placed on  a3.

Handicap   |   Odds Chess   |   Odds for Elo Differences

(2018-08-09)   Chess Titles
FIDE titles for over-the-board regular chess play.

Historically,  the title of  Chess Grandmaster  was first formally conferred by  Tsar Nicolas II  upon the five finalists of the  Saint-Petersburg tournament of 1914.  Namely:  José Raúl Capablanca,  Emmanuel Lasker,  Siegbert Tarrasch  Alexandre Alekhine,  and  Frank James Marshall.

When the title was instated by FIDE in 1950,  it was bestowed upon an initial list of  27 outstanding players  still alive.  Complex rules are now in place,  using  tournament norms  and a minimum Elo rating for the award of this top chess distinction and a few lesser titles,  as summarized in the following table:

Elo rating can be achieved anytime before tournament requirements,  if any.
Either SexWomen Only
International MasterIM2400
  Woman GrandmasterWGM2300
FIDE MasterFM2300  
  Woman International MasterWIM2200
Candidate MasterCM2200  
National MasterNM2200
  Woman FIDE MasterWFM2100
Woman Candidate MasterWCM2000
First Category1800 

Between 1977 and 2003,  FIDE awarded  31  Honorary Grandmaster  titles to chess players with outstanding records,  including  Jonathan Penrose  (brother of  Roger Penrose)  in 1993.  The courtesy couldn't be extended to  Rashid Nezhmetdinov (1912-1974)  who was already dead by then.  Since 2007,  no formal distinction is made between these and other Grandmasters.

The  Grandmaster  distinction was awarded shortly after his death to  Karoly Honfi (1930-1996)  by the FIDE Congress of September 1996,  in Yerevan.

Grandmaster (GM or IGM)   |   List of Grandmasters   |   FIDE titles   |   Chess titles
World Chess Federation (FIDE, Fédération Internationale des Echecs)   |   European Chess Union (ECU)
USCF   |   DSB   |   FFE   |   FSI   |   FEDA   |   KNSB   |   PZSzach
ECF   |   Chess Scotland   |   Welsh Chess Union   |   Irish Chess Union

(2018-09-09)   Famous Chess Clubs
Before and after formal World Championships were organized.

The first chess club was organized in Italy in 1550.  Come back later, we're
 still working on this one...

(2018-08-09)   Leading Chess Players throughout History
Before and after formal World Championships were organized.

In the Renaissance,  the leading chess players listed below were rarely challenged over-the-board in anything resembling a modern tournament.

Last column indicates main residence during peak years.
PeriodPurported Strongest PlayerAliveHome
1549-1559Paolo Boi 1528-1598Naples
1559-1575Ruy López de Segura c.1530-c.1580Salamanca
1575-1597Giovanni Leonardo Di Bona 1542-1597Naples
1597-1620Alessandro Salvio c.1570-c.1640Naples
1620-1634Gioachino Grecoil Calabrese c.1600-c.1634Naples

For a whole century after the death of Greco,  The Calabrese  (Le Calabrais)  the historical record doesn't single out any dominant player.  Meanwhile,  The nevralgic center of World-class chess migrated from Naples to Paris...

Diderot  and  Rousseau  reported  that the the undisputed World center of chess in the mid-eighteenth century was the  Café de la Régence  in Paris.  Around 1730,  François Antoine de Légal,  sire de Kermeur  emerged as the most respected player there.  (He spelled his own name  Legall.)

Legall's only extant recorded game is the fabulous 7-move checkmate below,  known far and wide as  Legall's mate.
Legall played this against  Saint-Brié  (Black)  in 1750:
1. e4     e5
2. Bc4    d6
3. Nf3    Bg4
4. Nc3    g6
5. Nxe5   Bxd1 ??
6. Bxf7+  Ke7
7. Nd5#
   Legall's mate

Légal mentored the young Philidor who dethroned him in 1755 and famously held on to the crown for 40 years, till his own death in 1795.  Philidor left Paris during the French Revolution and took on residence at  Parsloe's Coffee House  on St.  James Street  (that chess club was active from 1772 to 1825).  He was soon joined there by Verdoni,  the strongest player in Europe after Philidor  (according to Philidor himself).  Arguably, Verdoni was the strongest chess player in the World between Philidor's death (1795) and his own (1804).

Verdoni had learned chess at a mature age but was clearly superior to the other three leading players he left behind in Paris  (Bernard,  Carlier,  Léger).  Verdoni died in London on 25 January 1804  (in his Panton Street apartment).  His first name and date-of-birth are unknown.  He left his position as  Professor of Chess  in Parsloe's club to his star student  Jacob Henry Sarratt (1772-1819).

The  London Chess Club  was organized on the 6th of April 1807.  Chronologically,  it was the third club created in London  (after Slaughter's in 1715 and Parsloe's in 1772).  None of those had yet gained enough momentum to compete with the  Café de la Régence.  So,  after the passing of Philidor and Verdon,  the crown went back to France.  The three leading players between 1804 and the arrival of Deschapelles (1815) were Bernard,  Carlier  and  Léger  (in no particular order).

Tabulated below are the successive purported modern World champions rooted in that era,  with a few challengers of note  (shaded rows).

Last column indicates main residence during championship years.
1730-175528-53Légal de Kermeur1702-1792 Paris
(1737)Philipp Stammac.1705-c.1755 Aleppo / London
(1747)Sir  Abraham Janssen1720-1775 London
1755-179529-69André Danican Philidor 1726-1795Paris / London
1795-1804 Verdoni 17??-1804London
1804-1815Bernard / Carlier / Léger  Paris
1815-182135-41Alexandre Deschapelles1780-1847 Paris
1821-184026-45Louis de La Bourdonnais1795-1840 Paris
(1834)(36)Alexander McDonnell1798-1835 London
1840-184340-43Pierre Saint-Amant1800-1872 Paris
1843-185133-41Howard Staunton1810-1874 London
Adolf Anderssen1818-1879 Breslau
1858-186221-25Paul Morphy1837-1884 New Orleans
(1862)Louis Paulsen1833-1891  
30-58Wilhelm Steinitz1836-1900 London / NYC
1878-1886 Johannes Zukertort1842-1888 London
(1892)(42)Mikhail Chigorin1850-1910Russia
(1892)(30)Siegbert Tarrasch1862-1934 Munich
1894-192126-52Emanuel Lasker1868-1941Germany
(1895)(22) Harry Nelson Pillsbury1872-1906US
(1910)(35) Carl Schlechter1874-1918Vienna
(1913)(36)Frank Marshall1877-1944US
(1914)(33)Akiba Rubinstein1880-1961Poland
1921-192733-39José Raúl Capablanca1888-1942 Cuba
Alexander Alekhine1892-1946 Russia
(1929)(43)Aron Nimzovitch1886-1935 Copenhagen
1935-193734-36Max Euwe1901-1981 Netherlands
Salo Flohr1908-1983 Prague
(1938)Paul Keres1916-1975Estonia
Mikhail Botvinnik 1911-1995Leningrad
(1951)(27) David Bronstein1924-2006Moscow
1957-195836Vasily Smyslov1921-2010Russia
1960-196124Mikhail Tal1936-1992 Riga
1963-196934-40Tigran Petrosian1929-1984 Moscow
1969-197232-35Boris Spassky1937- Leningrad
1972-197529-32Bobby Fischer1943-2008 Brooklyn
Anatoly Karpov1951-Russia
(1978)(47) Viktor Korchnoi1931-2016Switzerland
Garry Kasparov1963- Russia
(1993)(28) Nigel Short1965-UK
1999-2000Alexander Khalifman1966-Russia
Vladimir Kramnik 1975-Russia
Vishy Anand1969-India
2002-2004Ruslan Ponomariov1983-Ukraine
2004-2005Rustam Kasimdzhanov1979-Uzbekistan
2005-2006Vesselin Topalov1975-Bulgaria
(2007)Vassily Ivanchuk1969-Ukraine
2013- now22-Magnus Carlsen1990-Norway

In the above table,  yellow highlighting  is for the 16 people who have been  undisputed  World champions at some point after the  Steinitz era.  Two of them  (Kasparov and Kramnik)  held the  PCA/Braingames title at the dates indicated in red during the period  (1993-2006)  when that title what distinct from the FIDE title.  Dates in black correspond to the World title recognized by FIDE.  The two titles were reunited in 2006 when Kramnik held them both.  He was then heralded as the  14th  modern  World Chess Champion.

World Chess Championship (WCC)   |   PCA (1993-1996)
World Senior Chess Championship (since 1991)   |   World_Rapid Chess Championship
Traité des Amateurs (Paris, 1775)
Deschapelles, the Pumpkin Farmer  by  Sarah Beth   (Chess.com, 2008-07-20)
Parsloe's in 1795, by Murray (1907)  by  Sarah Beth   (Chess.com, 2013-09-10)
Almost a Champion  by  Sarah Beth   (Chess.com, 2015-07-22)
Chess Masters  (Geni.com)
Les champions de l'Histoire: Stamma (50:27)  by  Vincent Di Martino  (2012-01-14).


Chess Jargon
Chess terms, classified by topic.

This is a work in progress...

 Come back later, we're
 still working on this one...

Types of Moves :

Situations :

  • Hanging piece :.
  • Attacker :.
  • Defender :.
  • Fork :  (fourchette).
  • Pin :  (clouage).
  • Skewer :  (enfilade).

Types of Mates :

  • Smothered Mate :  (mat à l'étouffée)  King blocked by its own pieces.
  • Corridor Mate :  (mat du couloir)  King blocked by its own pieces.
visits since January 28, 2010
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