H. G. Muller wrote on Fri, Jan 5, 2018 10:20 AM UTC:
Indeed, distinguishing pieces by (meta-)color is beneficial, and would also allow easy depreciation of end-games with unlike Bishops, like KBPPPKBP. I am not sure how that generalizes, BTW. End-games with unlike Ferzes did not seem particularly drawish. And logic dictates that the color binding should only be a handicap for the strong side, and not an asset for the weak side. So in KBPPPKXP it should not matter much if X is color bound or not. Yet when X=N this is not particularly drawish. The drawishness with X=B seems to be caused by the ability of the Bishop to stop large numbers of Pawns from crossing a diagonal.
Of course with multiple color-bound piece types mating potential can also critically depend on whether they are on the same or a different shade. Note that is Makruk it is beneficial to also consider Pawns as color bound, depending on the shade of their promotion square. KPPPK will be a draw if all Pawns promote on the same shade! It is a good question how to judge divergent pieces, such as the Berolina Pawn. My gut feeling is that you would have to judge them by their m component.
I have forgotten the exact number, but it surprised me how much stronger Pair-o-Max was than Fairy-Max. (I think over 50 Elo.) And this was just from recognizing Bishop pair and the drawishness. Where the latter was not even implemented through a material hash, so that I expected a significant slowdown from it. But the primary filter for the drawishness code is that the number of Pawns of the strong side should be <= 1, which is not the case throughout most of the game, and rather cheap to test. The largest overhead is actually keeping a count for each piece type (which probably costs less than updating a material hash key). Pair-o-Max doesn't recogize unlike-Bishop end-games, however, as these typically occur with many Pawns.
Indeed, distinguishing pieces by (meta-)color is beneficial, and would also allow easy depreciation of end-games with unlike Bishops, like KBPPPKBP. I am not sure how that generalizes, BTW. End-games with unlike Ferzes did not seem particularly drawish. And logic dictates that the color binding should only be a handicap for the strong side, and not an asset for the weak side. So in KBPPPKXP it should not matter much if X is color bound or not. Yet when X=N this is not particularly drawish. The drawishness with X=B seems to be caused by the ability of the Bishop to stop large numbers of Pawns from crossing a diagonal.
Of course with multiple color-bound piece types mating potential can also critically depend on whether they are on the same or a different shade. Note that is Makruk it is beneficial to also consider Pawns as color bound, depending on the shade of their promotion square. KPPPK will be a draw if all Pawns promote on the same shade! It is a good question how to judge divergent pieces, such as the Berolina Pawn. My gut feeling is that you would have to judge them by their m component.
I have forgotten the exact number, but it surprised me how much stronger Pair-o-Max was than Fairy-Max. (I think over 50 Elo.) And this was just from recognizing Bishop pair and the drawishness. Where the latter was not even implemented through a material hash, so that I expected a significant slowdown from it. But the primary filter for the drawishness code is that the number of Pawns of the strong side should be <= 1, which is not the case throughout most of the game, and rather cheap to test. The largest overhead is actually keeping a count for each piece type (which probably costs less than updating a material hash key). Pair-o-Max doesn't recogize unlike-Bishop end-games, however, as these typically occur with many Pawns.