Author: leonid
Date: 05:07:01 10/17/99
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On October 16, 1999 at 19:26:57, Jeremiah Penery wrote: >On October 16, 1999 at 17:51:46, leonid wrote: > >>To put in the chain of moves first the moves that give the check is simple - >>those moves can lead to the mate. Mate stop all the thinking, once the highest >>possible value is achieved. > > >It is true that these moves can lead to mate, but not very often. In fact, most >of these moves will be useless. Take this example: 1. e4 e5 2. Bc4 Nf6, then >the move Bxf7 is a check, but it is completely useless. I suspect this will be >the case for most checking moves. >My guess is that sorting moves first because they give check probably won't give >good results compared to other orderings. > >> Looking through the "tool" I found that the number >>of moves that lead to check is very small. This is the next reason for leaving >>those moves at the head of the chain. > > >This is true, but if the first move is very bad, you still have to search it >fully. Like in my Bxf7 example above, that is a bad checking move, but you >would still have to search it fully before searching other moves. This will be >bad for the branching factor in your program. > >>I looked into your description of the move ordering and I hope that I understood >>correctly everything that you have said. It is probable that our move ordering >>is very close but we explain it in a different fashion. >> >>Languages that we use are not the same. Mine is Assembler. Until now wrote >>everything for DOS but prepare to rewrite everything for Windows. And for what >>system you write? Or probably Java is already perfect for every system? > > >It's quite difficult to write a program in assembler, as it makes it difficult >to easily modify. I wish you luck. :) > >Jeremiah When I responded to your question at 1 o'clock in the morning (after working 5 hours by phone) I probably was too tired to see one reason. I speek about the usefulness to have the moves that make check, to the ennemy king, on the head of the list. Statistucally it is good for sure, I did the counting, but from logic point of view it is mainly because checking moves limites greatly number of moves that opposit side can execute. This probably is the reason for speeding of the logic. When during the generation of the moves for given ply, the indication of the moves that will check is found, this can be done in pretty quick way. More you have the nodes in the plys, more efficent legality and the checking aspect is accomplished. And for the same funny reason (just saying this because I reached this place) worst is you logic (more nodes you are forced to see in each ply) more your game will shine with its positions per second ratio. Leonid.
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