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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!

Rewan Demontay
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  • From the gap between your solution and mine I think that there is possibly some rule I didn't understand in your settings. – Arnaud Mortier Mar 28 '19 at 00:43
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    I feel like this should be in chess stack exchange. It seems more chess-y than puzzle-y to me – Prince North Læraðr Mar 28 '19 at 01:44
  • There was indeed much room for improvement. There still is, quite possibly. – Arnaud Mortier Mar 28 '19 at 16:51
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    Related, not a dupe: https://puzzling.stackexchange.com/q/30409/17297 and dupe from chess.se: https://chess.stackexchange.com/q/14610/9025 – Herb Mar 28 '19 at 21:23
  • The 105 has slightly different rules, although as far as I can tell, it would still be 103 under OP rules. – Joel Rondeau Mar 28 '19 at 21:40
  • @RewanDemontay Do you really count discovered checks as many times as there are squares where the moving piece can move? I didn't understand it that way. – Arnaud Mortier Mar 28 '19 at 22:32
  • Discovering check doesn't count if the moved piece also puts the king in check. Although as I reread, I think what you mean is it counts once, not twice, which means 105 again. – Joel Rondeau Mar 28 '19 at 23:38
  • I had been trying discovered checks only counting once, no matter where the piece moved – Joel Rondeau Mar 28 '19 at 23:39
  • Well I didn't even try discovered checks as it didn't seem very profitable, but under these rules it's something worth looking at. Then again it's unlikely that we find soon something better than 105. – Arnaud Mortier Mar 28 '19 at 23:52
  • Please don't move the goal-posts on a question like this. Changing your question after you've received answers is inappropriate, as it invalidates the answers you've received. It can even make those answers wrong, and adversely affect the reputation of those who answered. If you have a new or additional question, create a new post and ask it there; you can link back to this one if needed for reference. Right now the first thing people will see is the challenge to find maximum mates with no promoted pieces, and the existing answer obviously doesn't qualify; let's avoid that confusion, please. – Rubio Apr 13 '19 at 03:24
  • @RewanDemontay could you add in a screenshot of the position you have in your question? That would make the question more self-contained; I wouldn't have to click on a link to see your starting point. – bobble Jan 05 '21 at 15:23

2 Answers2

14

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.

Arnaud Mortier
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  • 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. – Matthew Barber Mar 28 '19 at 00:44
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    @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 :) – Arnaud Mortier Mar 28 '19 at 01:00
  • @RewanDemontay Thank you! It really makes things easier to think of. – Arnaud Mortier Mar 28 '19 at 01:19
  • @RewanDemontay Just made one last improvement with the ninth Queen. I'll stop here for now. – Arnaud Mortier Mar 28 '19 at 01:24
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    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. – Rewan Demontay Mar 28 '19 at 17:50
  • @RewanDemontay Well spotted! – Arnaud Mortier Mar 28 '19 at 19:07
  • @RewanDemontay I've made the picture, but I'm just checking another few possibilities to get to 100 before I add it :) – Arnaud Mortier Mar 28 '19 at 19:15
  • @RewanDemontay It also takes away a Queen mate from the Qf8. – Arnaud Mortier Mar 28 '19 at 19:41
  • First chess puzzle in a while that's really interesting – Joel Rondeau Mar 28 '19 at 19:44
  • There are lots of 99 permutations, just having trouble getting that last one. Currently trying rooks at b1,g1 but with either bishop or knight at d8, the other one can only manage a single mate. – Joel Rondeau Mar 28 '19 at 19:54
  • I managed to compose 100 some years back, but 105 is the record. Duplicate on Chess SE: https://chess.stackexchange.com/questions/14610/what-is-the-highest-number-of-different-mates-in-1-you-can-have-in-one-legal-p – Remellion Apr 25 '19 at 06:20
  • Why not add a pawn on d4? That makes 100. –  Oct 01 '20 at 04:40
  • @Anonymus25 It wouldn't be a threat, it would be a checkmate. And it would also block the path to a number of Queen checkmates, so in the end the result would be much less than 99 (if only it was legal!) – Arnaud Mortier Oct 01 '20 at 18:05
  • Oh, I mean d3, sorry –  Oct 02 '20 at 02:24
  • @Anonymus25 Same thing, it would block the way of plenty of queens and remove many threats. – Arnaud Mortier Oct 02 '20 at 06:11
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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.

Glorfindel
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