Author: Lenard Spencer
Date: 14:24:37 11/16/00
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On November 16, 2000 at 04:25:53, Ricardo Gibert wrote: >On November 16, 2000 at 02:51:47, Tony Werten wrote: > >>On November 15, 2000 at 20:40:16, Lenard Spencer wrote: >> >>>This question may probably be best answered by the problemists, but if what I'm >>>thinking is correct, it may be possible to make looking for double checks go a >>>lot faster than the brute force approach of looking all over the board for more >>>than one checker. >> >>The way I use it: >>first, can the piece just moved attack the king (lookup table)? If so get the >>direction in which it needs to travel (same lookup table) and check if there are >>any other pieces blocking. >> >>second, can a rook or bishop attack the king from the fromsquare of the moved >>piece. If so get the direction, then travel from the king in the direction of >>the fromsquare until you go off the board (no discoverd check) or bump into a >>piece (if piece=rook,bishop,queen then it's a discovered check) >> >>if ( first and second) then doublecheck:=true; >> >>Tony > >How about this position: > >[D]8/8/7k/6pP/8/4B3/7R/7K w - g6 > >The move 1.hxg6 is double check, but it is not clear to me how your algorithm >catches this. > In this example, the pawn move delivers a double check, but the pawn itself is not a checking piece. But it does serve to illustrate just how tricky it can be.
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