Author: Bruce Moreland
Date: 10:49:49 04/08/99
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On April 08, 1999 at 12:45:42, Steve Maughan wrote: >>> >>>Nope, I've never done this. >>This is really surprising! >Yes indeed it is! Bruce - I assume you have tried the "play the hash move >before generating other moves" idea and not found a benefit, yet I cann't see >any situation where this wouldn't be an easy win. > >I'm puzzled! I use a move table. A move is described as a pointer into the move table. At the time I originally wrote the program, I didn't have enough space in the move table for a pointer back to the source square. So if I had a pointer to the move table, I knew I had something that described a unique move, but I didn't know which piece was doing the moving, I had to store that seperately. I put one of these pointers in my hash table when I failed high, to remember what the best move was, and when I encountered this node later, I could figure out if I was trying to execute the same move that was in the hash table, and if so, order it highly. But I couldn't reconstruct the whole move itself from the pointer. All I knew was, for instance, that a white knight was coming from some unique place and going to e5. I had no idea that the knight was coming from f3. So for me, incremental move generation of this sort was not an option. That was back in the 16-bit world. I had to have that move table element as small as possible, since I jammed it into my code segment. My program is now a 32-bit program and that table is now about half a megabyte. But I still don't have the source square in the move table. If I put the source square in the move table and did incremental move generation, it might be a good thing, I could save quite a few move generations. But on the other hand, I would have to deal with the topic of this thread, and I would have to mess up a few loops and write some move verification code that would be a little icky given how rarely it is executed. That's the story. bruce
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