Author: Charles L. Williams
Date: 18:19:37 04/29/99
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On April 29, 1999 at 20:27:23, James Swafford wrote: >On April 29, 1999 at 15:31:54, Dann Corbit wrote: > >>On April 29, 1999 at 15:15:37, Pham Hong Nguyen wrote: >>>Could anyone explain how is different between PV and Killer moves? >>pv is preferred variation. That means that it is the sequence of moves the >>computer imagines is going to happen if both parties do their best. >> >>Killer moves are moves that look like really good ideas at first glance. In >>evaluating what move to make, you want to look at pawn x queen and stuff like >>that before some quiet sort of move. That way, if you run out of time, you will >>more likely have finished looking at the good moves. >> >>A pv is more or less the computer's current thinking about what the future >>sequence of moves is going to be. >> >>A killer move is something that goes into move ordering as far as which >>possibilities we should check out first and foremost. > > >To expand a bit on what Dann said, most programs keep a list >of 1-3 killer moves per ply of search. I _believe_ most programs >do not allow killer moves to be captures. > >A typical move ordering scheme would try the principal continuation >(or pv) move first, if one exist, followed by captures sorted >based on the expectation of material gain, followed by killer >moves and finally noncaptures and captures that are expected to >lose material. > >A move becomes a "killer move" by causing a fail high. >Whenever a move qualifies as killer, the least popular move >in your killer list gets replaced. > >There are countless other tricks, too. > >-- >James A good example of a killer move is a back rank mate, which can happen if immediate action such as a pawn move is not taken. Another is a knight forking the king and queen. Chuck
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