Kriegspiel problems Kriegspiel (chess)

kriegspiel used in chess problems. in these, usual variations introduced different black moves replaced variations introduced different announcements.

an example of kriegspiel problem shown @ right. white must checkmate black in 8 moves, no matter black bishop (it somewhere on dark squares) , no matter black plays. (note in real kriegspiel game, black not see white s moves, problem in white force win, 1 must assume worst-case scenario in black guesses correctly on each move.) example, 1. ra1?? draw stalemate if black bishop on a1. 1. nf2 bxf2 2. kxf2 (or rxf2) stalemate well. so, white should not move either knight or bishop, because either might capture black bishop accident. same reason, white rook should move light squares -- half of light squares reachable without visiting dark square along way.

the solution following: white tries play 1. rg2.

if move not possible (umpire says no), black bishop must on b2, d2 or f2. in case white can instead play 1. n(x)f2# (checkmate).
if move possible, made , black moves bishop. white still not know bishop is.

white continues 2. rg8.

if not possible, black bishop on g3, g5 or g7. white plays 2. be5. if black plays 2...bxe5, 3.nf2#. otherwise (any move black) 3. nf2+ bxf2 4. rxh2#.
if possible, white continues 3. rh8. (this safe -- black bishop cannot on h8 captured, because not on g7 on previous turn.) 4. rh5 5. rb5 (if not possible, 5. rh3 , 6.be5). 6. rb1 7. nf2+ bxf2 8. kxf2#.