H. G. Muller wrote on Mon, Sep 2, 2019 04:29 PM UTC:
This would not only bite you when you limit QS depth. Even if you do an unlimited-depth capture search, you would see phantom mates if you don't consider non-capture evasions (interposition or King withdrawal). You either must consider all evasions (effectively switching back to a d=1 search) on a check, or you should allow stand-pat even in the face of a check, assuming that a non-capture evasion that doesn't give away any score always exists. (Which would obviously make you overlook true checkmates in QS. This is not as bad as it sounds, as most checks are indeed not checkmates.)
QS explosion is a serious concern in general variant engines. MVV/LVA sorting might not be good enough to suppress plunder raids if capture modes other than replacement are possible. E.g. Lions in Chu Shogi are disastrous, when they can jump into the opponent's camp to a save square, and then then just sit there eliminating all neighors in combinatorially many different orders. Fire demons are even worse.
This would not only bite you when you limit QS depth. Even if you do an unlimited-depth capture search, you would see phantom mates if you don't consider non-capture evasions (interposition or King withdrawal). You either must consider all evasions (effectively switching back to a d=1 search) on a check, or you should allow stand-pat even in the face of a check, assuming that a non-capture evasion that doesn't give away any score always exists. (Which would obviously make you overlook true checkmates in QS. This is not as bad as it sounds, as most checks are indeed not checkmates.)
QS explosion is a serious concern in general variant engines. MVV/LVA sorting might not be good enough to suppress plunder raids if capture modes other than replacement are possible. E.g. Lions in Chu Shogi are disastrous, when they can jump into the opponent's camp to a save square, and then then just sit there eliminating all neighors in combinatorially many different orders. Fire demons are even worse.