5

I am looking for a position in which all possible moves are checkmate. This means, that if the player does not want to checkmate the opponent, because for example he feels sorry for him, even in that case he is forced to checkmate him. He cannot avoid it. Can you tell me an example? White or black does not matter.

Also, I feel this can be done only if there is a very small number of possible moves. For example 1 or 2.

  • 5
    Search for "selfmate" problems, in which White has to force Black to checkmate him. The positions before the last move of such problems are answers to your question. – RemcoGerlich Mar 25 '19 at 13:18
  • @RewanDemontay: of course, it was just a comment with a hint, not a full answer :-) – RemcoGerlich Mar 25 '19 at 19:52
9

I just remembered a class of chess problem; see item 267 of Tim Krabbé's Open Chess Diary (his whole site is highly recommended):

[Title "White mates in 7, Noam Elkies, 2004."]
[FEN "KBk5/P1P4p/2Pp3P/P6p/2p3rP/2P3pB/6P1/8 w KQkq - 0 1"]

Spoiler: White has some choices here, he can choose different move orders. But it's always checkmate on move 7, no matter what.

  • Nice, hadn't considered the possibility of deeper selfmates. – konsolas Mar 25 '19 at 21:54
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    @konsolas: this isn't a selfmate, just a normal mate in 7 that happens to be impossible to get wrong :) – RemcoGerlich Mar 25 '19 at 22:23
  • 1
    @RewanDemontay: and here all moves produce checkmate, after seven moves. Can't be avoided. Exactly the situation he asks for. – RemcoGerlich Mar 26 '19 at 7:47
  • 1
    @RewanDemontay: I don't see why. – RemcoGerlich Mar 26 '19 at 11:16
  • 2
    I mean I don't understand why this would be in any way too broad. Positions where one side can't avoid checkmating the other even if they wanted to. You have some examples, I have another type, that makes two relevant answers. Overbroad questions usually can't be answered at all or have tens of wildly different answers. – RemcoGerlich Mar 26 '19 at 12:21
6

The current record for most forced checkmates in a legal position with no promoted pieces is 29:

[Title "Harold Holgate Cross, The Problemist FCS Apr 1936, 2251"]
[StartFlipped "0"]
[fen "8/1b6/p1N5/P1r5/P3KPr1/QBk1NRP1/P2R1P2/4B3 w KQkq - 0 1"]

PDB has it at id P1178654. White is to move.

(For the record where the position must be legal and may have promoted pieces, see Rewan Demontay's answer.)

  • 1
    One source is Dickins & Ebert, "100 Classics of the Chessboard", no.94b. – Rosie F Mar 31 '19 at 6:08
3

I found two cases of FIFTY-FIVE forced mates with promoted pieces when looking at Tim Krabbe’s.

Journal 383: https://timkr.home.xs4all.nl/chess2/diary.htm

[Title "Ludwig Zagler Feenschach 1972"]
[Site "https://timkr.home.xs4all.nl/chess2/diary_17.htm"]
[Date "2019.04.17"]
[Round "-"]
[White "?"]
[Black "?"]
[Result "*"]
[SetUp "1"]
[FEN "1rB1Q1Q1/1PRQ3Q/2b2k2/2pQ1N1Q/4KRPp/5N2/1R6/B3nn1b w - - 0 1"]

[Title "Sampsa Lahtonen, 2008"]
[Site "https://timkr.home.xs4all.nl/chess2/diary_17.htm"]
[Date "2019.04.17"]
[Round "-"]
[White "?"]
[Black "?"]
[Result "*"]
[SetUp "1"]
[FEN "B3n1bb/1R6/4pN2/4KRPp/2pQ1N1Q/2b2k2/1PRQ3Q/1rB1Q1Q1 w - - 0 1"]

Tim Krabbe’s site (Journal Entry 334) states that there are 3 kinds of forced checkmate positions: legal, with promotions, legal, with no promotions, and illegal. The position here is with promotions of course.

Rosie F’s answer of 29 moves is the record without promotion, so her claim was corsrect. I just found her sources for her.

There are other interesting varieties on Krabbe’s website, so go take a look!: https://timkr.home.xs4all.nl/chess2/diary_17.htm


(I’m combining both of my answers.)

Here’s a simple position in which black is forced to checkmate White, for a simple demonstration is 2 pieces forced to mate in 3 different ways.

[FEN "k7/1R2Q2R/1p6/1Pp5/n1P5/3P2p1/2PNP1P1/2RKR2n w - - 0 1"]

Here’s an illegal position with 10 pieces total to deliver mate, and 14 total possible checkmates in total. The discovered mates are attributed to to moving piece that causes it.

[FEN "RN2k1NR/P3P2P/3PPP2/4pBp1/4PbP1/3ppp2/p3p2p/rn2K1nr w - - 0 1"]

The OP never said anything about a position having to be legal, so my answer here is technically correct.

  • Your second position has a simple cook of under-promoting to a bishop or knight, either of which will not result in checkmate. – Herb Wolfe Mar 25 '19 at 19:51
  • The first sentence is "I am looking for a position in which all possible moves are checkmate." Your second position fails that requirement. – Herb Wolfe Mar 25 '19 at 20:39
  • 2
    In your later updates, the bishops can move in a way that does not produce checkmate. – D M Mar 28 '19 at 3:10

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