Two questions

[bob]

I noticed after the fact that it was old.

[bob]

In micro-Max I search any number of null moves in a row, and it does not seem to hurt it significantly. With multiple null moves the reductions pile up, so although it might be a waste of time, it is hard to believe that it could ever be a significant waste of time.

Thta's how Toga does it currently - any number of null moves in a row. Changing always seems to lose elo, however.

Jerry

I'll make this a subject of a test run. To be clear, in Crafty, when I do a null-move search I always call search with a flag that says "no null next ply only". That needs to be changed. Anything else you do that is interesting? Such as letting nulls go deep into the endgame rather than turning them off when zugzwang becomes more common (Vincent D uses the second null to refute the first and supposedly avoid zugzwang problems. Never has worked for me, but I will give this a try, just to see if it is a positive, negative, or equal type of thing....

Thanks! It will be very interesting to see the results. I turn off null-move when entering a king and pawn endgame.

Jerry

I'll do that. Might take a day or two as I have some other test queued up at the moment...

It's been a long test Do you remember the results?

I was looking at the Fruit 2.1 code today because I'm convinced I have a search problem (newish engine developer here) and could not figure out how it (Fruit) was preventing successive null moves, but this thread made me realise it's implicit in eval() > beta. But, if you remove that, a la Toga, then it's going to just rip through to a QSearch - how can that be useful...?

Had to dig up the old info. I can not get double-null to work for me. All it seems to do is add overhead (tree gets bigger). Doing it in endgames was an issue (I enabled it period, even with no pieces).

However, last year I did go back to adaptive null-move that I had used until q-search checks were added (used to vary from 2 to 3, 2 closer to the tips. Now I am varying MUCH more than that, easily using R=6/7. I used this sort of formula years ago, but back when search depths were 8-10-12 plies. With today's huge searches, R can skyrocket.

[op12no2]

Now I am varying MUCH more than that, easily using R=6/7.

Gosh! OK, thanks.