From: Colin Paul Adams COLINA DEMON CO UK> Date: 4 feb 2000 Subject: CHU: solutions to A8 are flawed My program cannot solve A8 (in any sort of reasonable time - I left it running overnight). The published solutions are definitely flawed, as an obvious strong defence is overlooked: 1. +R - 2a, K x 2a 2. +DH x 4c, K - 2b 3. +DH x 4b, FL x 4b is the strong defensive move. One of the interesting things about this problem, is that 3. +DH x 4b - 4a, which avoids this strong defence, and preserves the Horned Falcon, doesn't lead anywhere, as the King promptly flees (as in the published solution), but the Horned Falcon is on the wrong square. Anyway, I believe there is still a mate, but it's rather tricky (clever use of the Horned Falcon) (and too long for the computer to solve unaided). As I am anxious to press on with all of this, I'll just give my analysis so far, and leave it for others to complete or refute. 4. +DK x 4b, K - 2c (K - 1c must also be looked at, but is weaker, at a cursory glance) 5. +DK - 4c, K - 1d 6. +DK - 3b, K - 2e if K - 1c, +R - 12c and Mate follows 7. +DK - 4c, K - 2f (K - 1d is disallowed by the repetition rule) if K - 3f, ... ? 8. +R - 12f, S - 3f or a King move leads to +DK/+R mate 9. +DK - 5c, Now it appears there should be a mate somewhere if the king goes forward, as we are pulling the Silver and side mover away from each other weakening the king's ability to resist. If the king moves back, then the absence of the Silver from the defence should leave it either mateable, or forced to run up the board again. I am aware that this analysis needs strengthening before it can be considered a full solution. -- Colin Paul Adams Preston Lancashire