Hard pawn endgame

[jhellis3]

This is difficult. The best problems solver = Crystal is clueless after 10 minutes. It don't reach enough depth I think.

It is a good test position. Unfortunately, Crystal has no mechanisms in place to deal appropriately with such positions. However, it is pretty clear how one might address the issue, so it should be relatively easy to fix. It will just take a bit of time to find the method with the best results for the least performance penalty.

[Jouni]

Have You found fix to false mate thing?
[d]8/8/2k5/8/3p4/Qp1p4/pp1p4/rrbK4 w - - 0 1

Correct mate is abandoned:

Crystal 270819 1th

1.Qf8 Kd7 2.Qf6 Ke8 3.Qg7 Kd8 4.Qf7 Kc8 5.Qe7 Kb8 6.Qd7 Ka8 7.Qb5 Ka7 8.Qd5 Kb8 9.Qc6 Ka7 10.Qc8 Kb6 11.Qd7 Ka6 12.Qc7 Kb5 13.Qd6 Ka5 14.Qc6 Kb4 15.Qc8 Kb5 16.Qc7 Kb4 17.Qc6 Ka5 18.Qb7 Ka4 19.Qb6 Ka3 20.Qa5#
+- (#20) Depth: 28/57 00:00:01 3197kN
1.Qf8 Kd7 2.Qf6 Ke8 3.Qg7 Kd8 4.Qf7 Kc8 5.Qe7 Kb8 6.Qd7 Ka8 7.Qb5 Ka7 8.Qd5 Kb8 9.Qc6 Ka7 10.Qc8 Kb6 11.Qd7 Ka6 12.Qc7 Kb5 13.Qd6 Ka5 14.Qc6 Kb4 15.Qc8 Kb5 16.Qc7 Kb4 17.Qc6 Ka5 18.Qb7 Ka4 19.Qb6 Ka3 20.Qa5#
+- (#20) Depth: 29/57 00:00:01 3908kN
1.Qf8 Kd7 2.Qf6 Ke8 3.Qg7 Kd8 4.Qf7 Kc8 5.Qe7 Kb8 6.Qd7 Ka8 7.Qc8+ Ka7 8.Qc7+ Ka8 9.Qd7 Kb8 10.Qc6 Ka7 11.Qc8 Kb6 12.Qd7 Ka6 13.Qc7 Kb5 14.Qd6 Ka5 15.Qc6 Kb4 16.Qc8 Kb5 17.Qc7 Kb4 18.Qc6 Ka5 19.Qb7 Ka4 20.Qb6 Ka3 21.Qa5#
+- (#21) Depth: 30/45 00:00:03 8620kN
1.Qf8 Kd7 2.Qf6 Ke8 3.Qg7 Kd8 4.Qf7 Kc8 5.Qe7 Kb8 6.Qd7 Ka8 7.Qd5+ Ka7 8.Qb5 Ka8 9.Qa6+ Kb8 10.Qc6 Ka7 11.Qc8 Kb6 12.Qd7 Ka6 13.Qc7 Kb5 14.Qd6 Ka5 15.Qc6 Kb4 16.Qc8 Kb5 17.Qc7 Kb4 18.Qc6 Ka5 19.Qb7 Ka4 20.Qb6 Ka3 21.Qa5#
+- (#21) Depth: 31/41 00:00:03 10010kN

This happens sometimes with longer mates.