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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A question regarding "The Horse Concoction"
Long ago in 2000, Tim Krabbe presented, a now classic, problem by Harry Goldsteen in his article “The Horse Concoction” on his site. It has blossomed across the Internet, as some of us know.
The task'...
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Could castling ever be proven to be legally allowed for sure if the first move is required to be a pawn move?
In retrograde analysis problems, castling is assumed to be allowed unless it could be proven that either the king or the rook has previously moved.
It is well known, of course, that one could never be ...
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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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Challenge: Create the longest set of moves where the game is able to be perfectly reproduced from only the current board state 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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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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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 would I detect dead position in a tablebase?
I am programming a tablebase for fairy chess, and would like to conclude the game if mate cannot be reached in any way. I guess this has to be detected when the evaluation (win in... / loss in... / ...
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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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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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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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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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Term to distinguish between two categories of illegal positions
Consider these two categories of illegal positions. First, e.g.:
Not having exactly one King of each color
Both Kings being in check
Pawns on the first or eighth ranks
Second, e.g.:
Having more ...
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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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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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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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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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Where are the non captured Black pieces?
[FEN "8/8/8/8/8/PP4PP/2PPPP2/NNBQKBRR w - - 0 1"]
Here is a problem from my blog once more. This is the position after White's 14th move. Seven Black pieces were captured during the game ...
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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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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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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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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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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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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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Where can I find these mentioned chess problems?
In his article “The Horse Concoction", Tim Krabbe mentions retrograde analysis problems that involve placing 10 rooks, knights, or bishops on the board for a mate in 1. The 10 rooks problem shown ...
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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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Attempting to create a retraction problem
I am trying to create a retraction problem, but I am unsure if it is sound, and I do not know where to find resources on them. I have two questions.
Is my problem correct? I am not giving a solution ...
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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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Generate an entire chess game up to a position
I recently found a chess problem YouTube video with this position.
[FEN "r4rq1/5p1p/p5kn/R1B1Q1b1/6p1/5p2/PNP2P2/1K6 w - - 0 1"]
I want to turn this position into an entire game of chess. ...
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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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Reach this position in four moves [duplicate]
I recently came across this chess problem. The requirement is to reach this position (starting from a basic board set up board) in 4 moves. How do you do it?
[FEN "rnbqkbnr/pp3ppp/2p1p3/8/4P3/8/...
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Mate in 1, then No Mate in 1, then Mate in 1
Anand and Bobby both are members of their school's chess club. And while cleaning up the games room at the end of the day, they saw a board with the following position:
[FEN "rbR1B1Q1/k1n1nN1p/...
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Retrograde problem websites
I am looking for a good chess website about retrograde analysis problems, but after a few searches, I haven't found anything. Are there any websites that you can recommend?
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Coordinates probem
[FEN "8/8/8/8/8/4R3/2N2R2/3N1k1K w - - 0 1"]
Given that this position could be reached in a legal game of chess, and that no piece was captured on the last move, are we seeing the board ...
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Where does the black king stand in this specific position?
[FEN "7r/pppppKpP/6P1/8/8/8/n7/8 w - - 0 1"]
Assume that the following position was reached in a legal game of chess. In the last 5 moves, no pawn has moved and no pieces were captured. The ...
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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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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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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 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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Retrograde analysis problem
Given that this position is legal, and could be reached in a legal game of chess, what were the two last half-movess, or one move for White and one for Black?
[FEN "5K2/8/6Pk/8/5Q1R/8/8/8 w - - 0 ...
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Help needed with a problem
On an empty board, how can you place a White king, two White, rooks, and a Black king so that White can give mate in 4 ways from that position?
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How many moves needed to reach this position?
"Homebase" is where all the surviving pieces are apparently on their starting squares. Here is a very easy new example proof game: can you find the unique shortest game that leads to this ...
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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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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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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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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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"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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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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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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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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