Solutions for Tutorial Problems {G}, {H} & {I}{G} After White moves, the game is pat, or Black is forced to take the pawn. So the game is dead. Black's last move was Kb8*Ma8. If M=Q/R the position is illegal. If M=B/N/0, Black has sole alternative Kxa7, but if M=B/0 then insufficient mating material remains. So M=N. This composition again mixes Class 1 & Class 2 elements. {H} If Black moved last from b1/2, then White has no prior move (a condition called "retropat"). So White moved last. So Black is to move now, but in pat. If White's last move was with a Pawn, then this blocks in the black king or the white bishop. The only candidates to avoid an impossible check are Bh2*Mg1 or Kf1*M'e1. M=N/B/0 or M'=B/0 does not relieve the retropat. M=Q/R or M'=Q/R means the capture was forced, so DR prevents it. So the last move was Kf1*Ne1. Check that M/M'=Q/R are legal retractions unless DR applies! {I} Whoever has the move, no mate can ever occur, so the position is dead. Every missing pawn promoted to a bishop. This costs 2 captures/file, from e to h, which together with the b-pawn captures makes 12 minimum. The d-pawns never captured, and the bishops on b1/8 did not just promote. Thus the last move could only have been a banal bishop move without capture, and the diagram would be illegal by DR. Thus any game from which this diagram came must have been prior to 1 July 1997. |