Questions tagged [retrograde-analysis]
Retrograde analysis is the method of deducing information by working backwards from a given position or outcome. This information can be about past positions of the same game, or may contain forward content, such as optimal play.
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How is this position possible in a normal game of chess?
A friend of mine gave me this problem. It goes like this.
In a normal game of chess, the white player checks the black's king with a rook and a bishop as in the following image.
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A mysterious mate in one
Here's a question that's a little off the usual format, but problem questions like this have been done before and are on topic, so here we go!
Question: Can you find the mysterious mate in one? The ...
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Given a legal chess position, is there an algorithm that generates a series of moves that lead to it?
Given a FEN board position, is there an algorithm that can return a PGN move list that evaluates to it from the standard initial position?
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Are there any illegal positions that are difficult to spot?
I have a question and I'm sorry if it sounds very uninformed, I'm not a professional chess player so my interest is mere curiosity. I was wondering if there are examples of illegal positions that ...
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Least number of moves to achieve a complete switchover of nonpawns in starting setup
[fen "RNBQKBNR/8/8/pppppppp/PPPPPPPP/8/8/rnbqkbnr w - - 0 1"]
During a comp, my friend an I had a team kill and we decided to make this position(legally) before drawing. Then we continued to find ...
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Can it be proven that 11. 0-0-0+ is legal in this position?
Because the chess site this was on takes its puzzles from real games and gives the move numbers, potential solvers knew that the following position was reached after exactly 10 moves by each player.
[...
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Is the position in this trick question reachable?
I found this trick question on r/Anarchy chess: White to move, mate in two.
[FEN "2R2RK/6PP/5P/3PN/P/1pQ3p/n1p1qbp/5brk w - - 0 1"]
[StartFlipped "1"]
The trick is that
But is ...
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Is there fiction dealing with retrograde chess analysis?
I am interested in retrograde analysis problems, where the question usually is: 'What was the last move made?' or 'Where did the piece stand on the board before it fell from the table?' etc. ...
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Prove that White is not allowed to castle here
A friend recently gave me the following weird chess problem to solve. I'm afraid that I'm struggling to see the key idea that would ultimately count as proof. From the position, intuitively speaking, ...
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Could a chess engine do retro analysis?
If I took a legal chess position, to what extent could an engine work out the previous moves? [in some other board games such as Othello such game reconstruction is done easily with an engine.]
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Can white win in this almost 20 year old puzzle?
It's White to move-can they force a win?. The left bottom is a1 as usual.
[FEN "4k2r/6p1/p4pKb/p2N3p/p7/p5Q1/p1n5/qrn5 w - - 9 9"]
Note for people who saw an earlier version: the position ...
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Beautiful retrograde analysis problem by Alexsey A. Troitsky
I saw this beautiful, subtle & accessible problem a couple of days ago, and wanted to share it with you folks. (It's by the ground-breaking endgame theorist who e.g. invented the "Troitsky line" ...
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What is the result? (Rules + puzzle)
[EDITED to include followup - EDIT 2 to include definition of position]
This is in part a genuine question on the FIDE Laws of Chess, and in part a small puzzle to solve.
Suppose that during a long ...
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Which methods can be used to prove that a position is illegal?
Given a board position, there are programs that try to find a series of legal moves that lead to it.
Are there algorithms that can do the opposite - prove that the position is not reachable by a ...
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Another problem - Find color of the pieces
Please help me to find the solution of this next problem by the legendary composer Andrej Kornilow. It appeared in Shakhmatnaya Kompozitsiya 41 issue in 2001 and it was dedicated to A. Lobusow on his ...
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Harry Potter Chess Analysis
So, I've been reading Harry Potter and The Philosopher's Stone. If you haven't read the book yet, or watched the movie, and you don't want any spoilers, stop reading this question. Continuing, there ...
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Identify a problem where a potentially winning move draws because of the 50 move rule
I'm trying to recall a particular chess problem. It's related to retrograde analysis. All what I can remember is this: it's an endgame where there is only one way to reach the position, and during ...
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How to solve proof games?
The following question deserves to be asked!
"I see a lot of proof game problems, where I am given a diagram and have to find the unique way to reach that position in the specified number of ...
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Which chess position requires the most moves to reach?
For each legal chess position there exist a shortest sequence of moves from the starting position to that position.
Which position requires the most moves to reach?
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Creating the current position having the rest of the game
It's a question a friend of mine brought up and I found intriguing.
Let's say you have the records of a game from a certain move to the end, using standard notation (i.e. Qf6).
Either assuming random ...
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About how to compose retrograde analysis problems
Are there any books or articles devoted to composing retrograde analysis problems? It seems that you would need some techniques beyond ones for standard problems.
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Open problems in chess involving maximum material imbalances
I am posting the present question since here Very unbalanced Chess Positions I have introduced three open problems (i.e., the third one, the fourth one, and the sixth one from the above), regarding ...
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Can a unique position be deduced if pieces are replaced by checkers (can see piece color but not type)
Inspired by a video where top players guess which famous game a position is from, except pieces in the position are replaced by checker pieces (so they can see the piece color but not type). Of course ...
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Can you mate with each of your 16 pieces on its original square?
An opinion poll conducted by problem composer Roberto Osorio over 10 master-level chess players in the Argentine Chess Club produced 100% wrong answers! :-)
When the right answer is posted here, I ...
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Mate in One the Missing King
The post "A mysterious mate in one" made me think of one of my last problems which is also a Mate-in-One with no black King:
[Title "White to move and mate in one"]
[FEN &...
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How is this retrograde analysis position legal?
On his page on Harry Goldsteen's "Horse Concoction,", Tim Krabbé gives this position by "N. Höeg, 1935."
[FEN "4k3/1p4pp/p1pQ1p2/1q1pp3/8/8/1K6/8 b - - 0 1"]
[...
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A problem rebus-reproduce the game
Here is a chess "rebus" problem. In this position, white and black circles correspond to White and Black pieces respectively. Each letter corresponds to exactly one piece type (king, queen, ...
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From Mate-in-3 to Mate-in-1
Here is my new problem in 3 steps - the key designates here the piece that moves first in the solution. An other way to reach a mate in one I hope you'll enjoy...
[Title "From Mate in 3 to ...
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Find color of the pieces
Given the following position, what colour are the pieces and what was the last move played?
[FEN "B1KRN3/PP6/2QK1R2/8/8/8/8/8 w - - 0 1"]
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Pal Benko's final problem
EDIT: Link added
One of my chess heroes, Hungarian GM Pal Benko, is no longer with us. He overcame many difficulties in his early life to live one which was rich and full, and reached the age of 91 ...
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About retrograde analysis
Raymond Smullyan wrote some great books with Retrograde Analysis chess puzzles. I know of two, are there others?
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Do any unique proof games feature an en-passant capture?
Most positions that could be reached, in a specified number of moves, after an en passant capture could be reached just as well without one, suggesting that such positions could not occur in unique ...
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Retrograde analysis of a position in "The Flanders Panel"
Has anybody tried to verify the retrograde analysis of a game from the book "The Flanders Panel" by Pérez-Reverte? So far, I have found only a board reconstruction in a post on The ...
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Problem: reconstruct the game
In the following position, each side has made exactly 4 moves (8 in total).
[fen "rnbqkbnr/pp3ppp/2p1p3/8/4P3/8/PPPP1PPP/RNBQK1NR w KQkq - 0 1"]
I need to find what these moves were.
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"Knight rebus"-Decipher an encoded chess position
Here is a knight rebus. Each letter represents a different type of piece.
Uppercase letters are one color and lowercase letters are the other.
Determine the position. If possible, also determine the ...
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Challenge: Create the longest game determined only by the final diagram and move number
The challenge is to create the longest list of half moves whereby an AI could re-create that list of moves perfectly, only given the ending board state and the number of moves.
As example I will first ...
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Legal positions with one color to move only?
Most positions in chess can be reached with both black or white to move.
Some positions are only legal with one color to move. One such position is the starting position, which famously can't be ...
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Position where last x halfmoves are determined
What is the largest integer x such that there exists a position such that:
That position can occur in a legal chess game
It is possible to prove at least x halfmoves have been played
It is possible ...
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When can you tell which pieces are 'White' from a position where the pieces are colored red and green and you know whose move it is? [duplicate]
Suppose you come across a chessboard where the pieces are colored red and green and there are no labels on the squares. You don't know which move number it is.
What are the positions where, by only ...
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What are "monochromatic" retrograde analysis problems?
What does it mean when a retrograde analysis problem is qualified as being "monochromatic" ?
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A conditional retrograde analysis problem
Here is the problem-find a chess game that begins with 1. e4 and ends on the fifth move with knight takes rook mate, which determines who gives the mate.
This is a famous puzzle. For additional ...
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Problem: Find White's second-to-last move
For the following position to occur in legal play, with Black on move, what would White's second-to-last move need to have been? Note that Black is checked by two pieces on the h1-h8 file and two ...
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Brainteaser puzzle
So... initial position is
[FEN "7k/8/6KB/8/p7/8/Q7/8 w - - 0 1"]
Now... Neither white's king nor queen has moved in the previous five moves. In addition, no pieces have been captured by ...
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Seeking a particular problem
I recall seeing a problem in Games magazine, probably in the early 1990s, that required the solver to deduce that a capture en passant was possible (not just because that's the only way to get a ...
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Do you know this proof game?
I'm not familiar with this proof game.
[FEN "r2qk1nr/ppp1pp1p/2n1p2p/8/8/1P6/NPPPPPPP/R3K2R w KQkq - 0 1"]
What square was the white queen captured and how?
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How many more squares can you attack?
(Inspired by this cool problem)
Let’s say it’s White to move. Let A = the number of squares currently attacked by White, and B = the number of squares attacked by White after White’s next move.
What ...
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Prove the pawn's color and the knight's position
I was recently given a retrograde analysis problem to solve. Even though I've managed to at least intuitively get close to an answer, I don't know how to put it in the form of an acceptable proof. For ...
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Which piece was captured last - knowing that this position was reached in the minimum number of moves possible?
This is a puzzle that I made a while ago, but never really published anywhere before (although I posted it on an obscure Dutch telegram channel).
The question is simple: what was the piece that was ...
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Can we say for sure that Black's king has not moved?
The following position appears as the 7th puzzle of Raymond Smullyan's Arabian Knights, a book about retrograde analysis.
[FEN "3qk2r/p2pp1bp/bpp2n2/8/3N3Q/1PN1P1P1/P1PPP2P/3K1n2 w - - 0 50"]...
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What was Black's last move?
It's White to move. What was Black's last move, and what could have happened before that?
[FEN "8/8/8/8/8/3P2P1/3P2Pk/2KR3N w - - 0 1"]
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