Author: Tony Werten
Date: 05:49:08 11/16/00
Go up one level in this thread
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 Obviously en-passent and castlemoves have to be treated different. Castling cannot be a doublecheck. En passant: you have to check the targetsquare to. Tony > >The move 1.hxg6 is double check, but it is not clear to me how your algorithm >catches this. > >>> >>>Has anybody seen anything written on the subject of what makes a double check a >>>"legal" double check? I mean, one that can only happen in the course of a game? >>> One example, for a pawn to be involved in a double check (not counting >>>promotions), it can only be on a capture, discovering a rook or queen behind it. >>> >>>I have been looking long and hard at this, and it seems to me (of course I'm >>>only a 1250 OTB player) that there are only certain circumstances that will >>>allow a legal double check. I would like to locate any material like this to >>>see whether I am right or wrong. >>> >>>Thanks in advance for any help.
This page took 0 seconds to execute
Last modified: Thu, 15 Apr 21 08:11:13 -0700
Current Computer Chess Club Forums at Talkchess. This site by Sean Mintz.