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Just an interesting idea for a puzzle that I had

So, I decided to see how many possible checkmate I could theoretically make, in a legal position that can be legally reached.

Always assume that the two players are mutually cooperating. It would be the checkmater’s, black in this case, turn to move. How many possible checkmate could you make for black to possibly deliver?

A move only counts as a possible checkmate is if it checkmates right away. If a piece can move to two or more squares to deliver a mate, each possibile move counts as a checkmate threat.

Discovered checks that result in checkmate only count if the piece that moves to allow the check do not deliver checkmate themselves.

Promotions by a pawn to do a checkmate, in the case that mate can be done by either a rook or a queen, count as only one threat for each promoting pawn.

Always make sure that the to-be checkmated side has a piece or two so it will not count as a stalemate if the position would be otherwise. This is to make sure the game has stayed a legal one. Stalemates always result in a disqualification. I will be the judge if it, for this is my question.

As such, here is my record of 26 possible checkmates threats:

https://www.apronus.com/chess/pgnviewer/?p=An_____n____n___P__r_r_P__n_K_n____r_r______n____n_____n_______qk0

(There’s two mating threats from each of the knights, rooks, and the queen.)

Try to beat me, even by 1 if you must!

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  • $\begingroup$ From the gap between your solution and mine I think that there is possibly some rule I didn't understand in your settings. $\endgroup$
    – Arnaud Mortier
    Commented Mar 28, 2019 at 0:43
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    $\begingroup$ I feel like this should be in chess stack exchange. It seems more chess-y than puzzle-y to me $\endgroup$
    – Prince North Læraðr
    Commented Mar 28, 2019 at 1:44
  • $\begingroup$ There was indeed much room for improvement. There still is, quite possibly. $\endgroup$
    – Arnaud Mortier
    Commented Mar 28, 2019 at 16:51
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    $\begingroup$ Related, not a dupe: puzzling.stackexchange.com/q/30409/17297 and dupe from chess.se: chess.stackexchange.com/q/14610/9025 $\endgroup$
    – Herb
    Commented Mar 28, 2019 at 21:23
  • $\begingroup$ The 105 has slightly different rules, although as far as I can tell, it would still be 103 under OP rules. $\endgroup$
    – Joel Rondeau
    Commented Mar 28, 2019 at 21:40

2 Answers 2

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I have

99.

As shown here:

Credit to Rewan for the Knight on the right. chessboard

Note: the position is easily seen to be legal, as the knight can make back and forth moves while the black pieces get into position.

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  • $\begingroup$ You'd still need a black king somewhere on the board for it to be a legal position. There are a few options with your solution though, such as at H1. $\endgroup$
    – Matthew Barber
    Commented Mar 28, 2019 at 0:44
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    $\begingroup$ @RewanDemontay The reason it's now 78 and not 82 is because I realized that the Queens are not as symmetric as I initially thought: there are no e9 or i5 squares :) $\endgroup$
    – Arnaud Mortier
    Commented Mar 28, 2019 at 1:00
  • $\begingroup$ @RewanDemontay Thank you! It really makes things easier to think of. $\endgroup$
    – Arnaud Mortier
    Commented Mar 28, 2019 at 1:19
  • $\begingroup$ @RewanDemontay Just made one last improvement with the ninth Queen. I'll stop here for now. $\endgroup$
    – Arnaud Mortier
    Commented Mar 28, 2019 at 1:24
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    $\begingroup$ If you add a black knight on h6, it will be able to have to two checkmates. Since it blocks only one other mate, the h4 queen capturing the h8 white knight, you will have added one more possible mate, bumping up the number to 99. $\endgroup$
    – Rewan Demontay
    Commented Mar 28, 2019 at 17:50
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Posted here by user @bof on Chess Stack Exchange:

enter image description here

105 mates — Nenad Petrovic, Sahovski Vjesnika 1947 (Chess Problem Database)

In this position any check is mate. There are 3 knight mates (c4, g4, f7), 23 discovered mates (14 moves for the rook on c7, 9 for the bishop on b5), and 79 queen mates: 1 on a1, 2 on b2, 3 on c3, 4 on c5, 6 on d4, 3 on d5, 6 on d6, 3 on e1, 2 on e2, 4 on e3, 4 on e4, 2 on e6, 4 on e7, 3 on e8, 5 on f4, 3 on f5, 6 on f6, 4 on g3, 5 on g5, 2 on g7, 3 on h2, 3 on h5, and 1 on h8, for a total of 105 mates.

Under the specific rules of this question, Re7++ and Rc5++ don't count (or do you mean they don't count as two checkmates each?), so that would be 103.

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  • $\begingroup$ (I now realize that the answer has been mentioned in a comment under this question as well. Sorry, that happens to comments ...) $\endgroup$
    – Glorfindel
    Commented Jan 5, 2021 at 8:27
  • $\begingroup$ What extra rules?!!!! It's 105 checkmates total. $\endgroup$
    – Rewan Demontay
    Commented Jan 5, 2021 at 13:19
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    $\begingroup$ @RewanDemontay Discovered checks that result in checkmate only count if the piece that moves to allow the check do not deliver checkmate themselves. $\endgroup$
    – Glorfindel
    Commented Jan 5, 2021 at 13:22
  • $\begingroup$ Oh, right. Eh well. $\endgroup$
    – Rewan Demontay
    Commented Jan 5, 2021 at 13:23
  • $\begingroup$ Still 105 either way. $\endgroup$
    – Rewan Demontay
    Commented Jan 5, 2021 at 13:23

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