Mate in 292 moves

  

Mate in 292 moves


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Thibault de Vassal    (2006-10-19)
Mate in 292 moves

Otto - Titus Blathy (1860 - 1939), Hungary
Vielzügige Schachaufgaben, 1889
(10 + 12)
Mate in 292 moves

Illegal position


Now you may try to solve the problem, but my question is : Why is this position illegal ??


ChessPosition (see diagram)
8
7
6
5
4
3
2
1
a b c d e f g h




Wolfgang Utesch    (2006-10-19 20:19:50)
Mate in 292 moves

Hello Thibault, I think the pairs of double pawns on e-g-h-lines are impossible to achieve out of the normal chess start position! Wolfgang


Wolfgang Utesch    (2006-10-19 20:47:01)
Mate in 292 moves

The white pawn h4 cannot reach its position without striking the black g-pawn - but this g-pawn is still there! Wolfgang


Wolfgang Utesch    (2006-10-19 20:56:51)
Mate in 292 moves

More accurate: The white pawn h4 cannot reach its position without striking the black g- and h-pawns - but this g- and h-pawns are still there! In combination with the black g-double pawn an the black h5-pawn, which position need to strike the white g- and h-pawns is it unpossible to reach out of the normal chess start position! Wolfgang


Thibault de Vassal    (2006-10-19 23:07:16)
Re: Mate in 292 moves

Can't the pawns strike other pieces, rooks, bishops... ?!


Wolfgang Utesch    (2006-10-20 07:22:10)
Mate in 292 moves

You're right! But this position seems to be so artificial, that I can't believe to reach it in order with all chess rules out of a normal chess start position. And I can't see any other problem with this position. Wolfgang


Gino Figlio    (2006-10-20 07:56:02)
too many pawn captures for white

4 white pawns are still in their original post. There are however 3 doubled pawns. The minimum number of pawn captures to achieve this would be 7, but black has only lost 4 pieces(2 rooks and 2 bishops); therefore the position is illegal.


Wolfgang Utesch    (2006-10-20 09:39:00)
Mate in 292 moves

Yes, Gino, you are right! All pawns on board, so the double pawns can reach their position only by striking of other figures. For this position black should have had 9 (!) other figures (h4 by 2 figures; g5 by 3; e6 by 4) - but only 4 are missing. Wolfgang


Thibault de Vassal    (2006-10-20 14:09:35)
Re: Mate in 292 moves

The minimum number of pawn captures is 8, that's a funny problem :)


Now here is the solution for the mate :

http://www.chess-problem.com/classic4.htm


Elmer Valderrama    (2006-10-20 18:23:22)
other surreal mating positions

..I mean mating as in mate in 2,3..;)

There are far more surreal positions even with fancy names for each of them however no-one calls them "illegal" why is it? ..just wondering..


Thibault de Vassal    (2006-10-20 18:48:37)
surreal, not illegal

Because it's "possible" to reach these positions on the chessboard during a game !?


Elmer Valderrama    (2006-10-20 21:24:52)
quite a lot!

Thanks for your comment Thibault

Out of curiosity, just searched the Chess Problem Database Server and found a lot (+200!)of chess problems that have been found illegal one way or the other (not sure yours is listed there but I presume it is)


Elmer Valderrama    (2006-10-20 21:55:18)
retrograde analysis

from math.harvard.edu

"Legal position (n.): a position that can be reached from the initial array by game consisting entirely of legal moves, however bizarre. Conventionally every chess problem should have a legal position. Naturally then, an illegal position is a position that cannot be reached by a legal game. For instance, a position in which one side has more than 8 pawns, or has both White and Black Kings in check, is illegal (why?). So is any position with a White Bishop on h1 and White pawn on g2 (why?), such as the following mutual Zugzwang (q.v.), which Lewis Stiller discovered in the course of an exhaustive computer search: White Kg6, Bh1, Pg2; Black Kg4, Pg3. The Kniest position White Kc8,Pb6; Black Ka8,Pa7 (seen above under Helpmate) is legal BTM, but not WTM since Black is in ``retro-stalemate'': Black could not have made a legal move to reach this position. [Thus this position can be set as a Helpmate in Two but not a Mate in One (or ``helpmate in 0.5'').] There are positions that can be recognized as illegal only after extensive retrograde analysis. To prove that a position is legal, one need only exhibit a single legal game reaching the position; such a game is called a proof game. Some retrograde analysis may still be needed to construct a proof game."

I bet nowadays there exist a problem solving chess engine which can give such a 'proof game' in 0.0001milisec (as the moves maybe bizarre, no need to evaluate positions, just to check them for legality)