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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Is Retro Zugzwang possible?
What is just a zugzwang is clear. This is when, in a normal good position, a side is forced to make a move, and any move made leads to a loss.
Accordingly, in Retro moves are made not forward, but ...
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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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Lower bound on the number of moves to reach given position
I'm trying to analyze opening positions using the Lichess evaluations database. Loading the entire database into memory is somewhat costly, so I'd like to filter out positions that occur after, say, ...
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Do endgame tablebases only handle legal positions?
The title is my question for now.
I also wonder if similar legality concerns may reduce the number of input FENs as checkmates used as input to the retrograde proofing or construction process. In ...
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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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Missing move in a chess match due to lousy annotation
I am a beginner in championships (well, and in chess in general). The other day I played a match that I can't analyze because there is an error in the annotation sheet.
[FEN ""]
1. e4 e5 2. ...
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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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Max number of promoted units on the board in a monochromatic game
A whimsical question just occurred to me. I think I have an answer, but I thought I would share it here as a puzzle.
What is the maximum number of promoted units that can appear simultaneously on the ...
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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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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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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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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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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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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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