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Subject: Re: Improvements in BF makes my MoveGen suck =(

Author: Uri Blass

Date: 00:30:16 06/28/03

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On June 27, 2003 at 21:13:46, Russell Reagan wrote:

>On June 27, 2003 at 19:04:04, Steve Maughan wrote:
>
>>I don't agree.  Perft is *quite* a good thing to optimize.
>
>Perft is important, but that statement can be misleading. People confuse "perft
>speed" with "search speed" somtimes, and they don't always translate.
>
>You can use tricks to speed up your perft that you don't (or can't) use in your
>search, and those speedups aren't important as far as engine strength is
>concerned. See the discussion of Movei and Yace below for examples.
>
>>There are really
>>four fundamental foundations of a good chess program -
>>
>>1) Evaluation
>>2) Move Ordering
>>3) Make / Unmake moves
>>4) Generate Moves
>
>3 and 4 can be grouped into "board representation", IMO. I think the main goal
>in choosing a board representation is to "not hinder the engine's future." Speed
>is a secondary goal IMO.
>
>I think most people spend too much time deciding on a board representation and
>working on making things fast, because that is what you do first. Choose a good
>board representation that is 1) fast enough, and 2) gives you something for
>free.
>
>Also I think you're missing forward pruning from your list.
>
>>It's other advantage is that you can't cheat with perft - i.e. for any given
>>position there is a certain number of nodes that represent perft 5.  This is in
>>contrast to Node Per Second where it's not clear what constitutes a node.  So
>>you can see and objectively measure your perft times against other engines.
>
>Ah, but you can "cheat" at perft :) I guess it's not really cheating, but you
>can make it MUCH faster than your movegen/make/undo. For instance, Movei
>calculates perft at over 11Mnps on my machine, and searches at around 350Knps.


I think that my way give the right importance for gen when making and unmaking
the last move give the wrong weights because all the idea of perft is to test
mainly the speed of generating moves and not the speed of making them(otherwise
it is less similiar to what I do in normal search).

Uri



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