Author: rasjid chan
Date: 13:02:44 04/15/04
Go up one level in this thread
On April 15, 2004 at 14:21:36, Robert Hyatt wrote: >On April 15, 2004 at 14:05:42, rasjid chan wrote: > >>On April 15, 2004 at 12:22:43, Stefano Gemma wrote: >> >>>On April 15, 2004 at 05:01:54, rasjid chan wrote: >>> >>>>After reading the recent post on non-recursive search, I decided to >>>>implement it. My guess is that maybe search function call overhead >>>>may be too high as I have a host of local variables that cannot be reduced. >>>> >>>>My approach is direct and simple, an attempt to immitate recursion by >>>>creating my own search stack and managing it instead of allowing C function >>>[...] >>> >>>In my old program Drago for Dos (1993's sources are at www.linformatica.com), i >>>don't use recursive search. The same was for Raffaela. Both are written in >>>assembly. I use a fixed area of memory to old variables for any node (it is >>>something like an array of struct, but in assembly). Debugging a non-recursive >>>engine in assembly, with a lot of conditional jump was very hard. My last >>>engine, Freccia, don't use non-recursive search but still i don't use stack for >>>variables but the old array of struct. I think this is the better way to do, in >>>my program. Debugging is easyer and i can preset some fixed constant depending >>>on the node depth. >>> >>>Ciao!!! >>> >>>Stefano Gemma >> >>To do non-recursive search in assembly would be too tough for me, even with >>easy C the debugging can be tricky. >> >>I am not sure I know or use programming terms / naming correct. What I mean >>by stack is my data of array of search_stack_struct type which I create. >>Then make/unmake a move becomes ++ply, ++ps, --ply, --ps >>where ps is a pointer to my search_stack_struct. So using this pointer ps, >>I store / restore my alpha,depth,pointer to current move made / first or >>last move in my move list, etc. In this way and with care we can try >>non-recursive search and I think there should not be reasons why it cannot >>be made better than recursive search. > > >I don't think there is enough difference to measure. Cray Blitz was >non-recursive as early Fortran didn't allow recursion. Crafty has been >recursive from the start. Procedure call overhead is _not_ significant on a PC, compared to all the work done inside one such call. =========== This is the thing i don't know nor am sure, and if measured would probably be as you say - so nothing gain. But I am also thinking that the a transparent stack may be of use later as there must be some usefulness to pruning, etc in knowing what the state of the nodes are nth ply down; I have yet to know what or how. Thanks Rasjid > >Non-recursive offers some advantages in a parallel search, but as Crafty shows, >a recursive parallel search can (and does) work well. It is just more >complicated in a recursive search and there are things you can do in >non-recursive that you can't do in recursive easily. > > > >> >>Best Regards >>Rasjid
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.