Author: Dave Gomboc
Date: 04:41:45 10/25/02
Go up one level in this thread
On October 25, 2002 at 07:35:13, Alessandro Damiani wrote:
>On October 25, 2002 at 07:19:52, Uri Blass wrote:
>
>>On October 25, 2002 at 07:08:13, Alessandro Damiani wrote:
>>
>>>>>The implementation of generating moves in chunks is easily done by encapsulating
>>>>>all work in a method that returns the next move:
>>>>>
>>>>> Move nextMove(int ply, ...)
>>>>>
>>>>>The value 0 is returned, if there is no move anymore.
>>>>>
>>>>>The method nextMove() has a state for each ply: in which generation phase it
>>>>>currently is. For instance, our move ordering is
>>>>>
>>>>> 1. hashmove
>>>>> 2. winning captures
>>>>> 3. killer 1
>>>>> 4. killer 2
>>>>> 5. equal captures
>>>>> 6. non captures
>>>>> 7. losing captures
>>>>>
>>>>>We define the following phases:
>>>>>
>>>>> PHASE_HASHMOVE 0
>>>>> PHASE_GENCAPTURES 1
>>>>> PHASE_POSCAPTURES 2
>>>>> PHASE_KILLER_1 3
>>>>> PHASE_KILLER_2 4
>>>>> PHASE_EQUALCAPTURES 5
>>>>> PHASE_GENNONCAPTURES 6
>>>>> PHASE_NONCAPTURES 7
>>>>> PHASE_NEGCAPTURES 8
>>>>
>>>>Today I also have phases nit clearly less phases than you.
>>>>
>>>
>>>As I stated above, this is just an example. I have got more phases.
>>>
>>>Just to be clear: only phase 1 and phase 6 generate moves (in this example).
>>
>>I understand now but I still do not understand.
>>You do not generate moves in phasehashmove?
>>
>>what do you do exactly
>>Do you say that
>>you check if the hash move is legal and if it is legal you generate it?
>>
>>What do you do in phase 1?
>>Do you compare all moves with the hash move to promise that you do not have it
>>again in your list or do you generate it again and only in the sort move you
>>ignore it.
>
>Below is an excerpt from my engine Fortress.
>
>Just to make you understand my notation: I emulate OO in C. So I access method
>isValid() of module Move by writing Move_isValid().
>
>--- nextMove(ply, ...) ---
>
> ...
> Move m;
>
> switch (phase[ply]) {
> case PHASE_HASHMOVE:
> phase[ply]= PHASE_GENCAPTURES;
>
> // establish invariant: last[ply] points behind the last entry in the
> // move list
> MoveGenerator_last[ply]= MoveGenerator_last[ply-1];
>
> m= MoveGenerator_hashMove[ply];
>
> if (Move_isValid(m))
> return m;
>
> // it applies: !Move_isValid(m)
> // continue with next phase:
>
> case PHASE_GENCAPTURES:
> ...
>
>--------------------------
>
>You notice the following:
>- I don't generate the hashmove, since I get it from the hashtable
>- I test for validity of the hashmove with method isValid(Move m)
>
>The same method is used for killer moves, since they already exist. I don't need
>to generate them.
>
>As you can see, this is optimal: if the hashmove produces a beta cut-off no move
>is generated. Method isValid() is fast with bitboards. ;)
>
>Alessandro
I think one thing that Uri wants to know is how you avoid making sure that every
move that you generate later is not a) the hash move and b) any other move that
you've already searched. If I understand his situation correctly, he doesn't
have a way to do this efficiently at the moment.
Dave
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