On the board, there are 2 queens (of the same color) placed on random squares. The opposing side has only a king, placed on a random square (and not in check). There obviously exists a mating sequence. What is the biggest possible 'n' such that there is a forced Mate in 'n'? In other words, given the above situation, what is the upper bound on the minimum number of moves required to give a checkmate?
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I don't have an answer to your question but I have a comment that may be relevant to your research. This link has mate in 2 puzzles with two queens vs a lone king: apronus.com/chess/puzzles/mate-in-2/?KQQvK– MichalRyszardWojcikAug 9, 2020 at 10:37
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1"There obviously exists a mating sequence." Except for stalemates.– TheSimpliFireAug 9, 2020 at 12:41
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1@TheSimpliFire The solution to that is not to stalemate.– Comic Sans StrikephimAug 10, 2020 at 1:58
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3@You'rebadandshouldfeelbad I think the stalemate comment was intended to point out the possibility that the "random" starting position in the question might be stalemate.– Andreas BlassAug 11, 2020 at 3:54
1 Answer
The longest KQQ-K mate whilst maintaining optimality is a mate in 4.
[FEN "8/8/8/3k4/8/5K2/8/4Q2Q w - - 0 1"]
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1
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3@fedorqui, in that case, 2. Qc7 (Kd5 3. Qe4#) (Kd3 3. Qe3#) mate in 3.– justhalfAug 10, 2020 at 8:07
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Yes, this seems right. I played a lot in an analysis board and couldn't find a position which requires mate in 5. Nov 12, 2021 at 16:36