Problems for 9/7/10

Excellent, though the warden to himself as the inmates groaned trying to solve the three brain cramping puzzles he had dug up for solving. The only embarrassment had been the complete failure of the prison guards to invent a fourth problem to torment them further.

The problems were so hard that only one inmate among the mass of them was able to find a solution to each. The reign of terror continued the next day....

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2Kb4/7B/1p1p2N1/4pPPp/R1P1k1qQ/3p1N2/8/1n3RB1 w - - 0 1
Mate in 2
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++++

8/5p1k/7p/P5pp/1p2pn1n/RP4pP/6P1/K2B4 b - - 0 1
helpmate in 4
black moves first; white's 4th move mates; white and black cooperate.
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++++

8/3n2r1/3K1b2/2P3q1/8/6r1/4b3/5k2 b - - 0 1
series helpmate in 17
black makes 17 moves in a row [no checks until the final move], then white makes one move that checkmates black.
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++++

rn1q1rnk/B1pppp1p/1pN2p2/5R2/P7/2P4P/1PP1P2P/1N2K1QR w K - 0 19
pg 18
position after black's 18th move. how did the game go?
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