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Larry Kaufman

Joined: 10 Jan 2010
Posts: 1229
Location: Maryland USA

Post subject: Re: When does a cut-node became an all-node?    Posted: Tue Mar 27, 2012 7:17 pm

diep wrote:
 lkaufman wrote: Please clarify -- are you simply talking about increasing the null move reduction (like from 3 plies to 4, or from 4 to 5) when the score is more than a pawn plus? If this is what you refer to, its effect is pretty minor, and everyone is using this now.

I had editted my post. Yes, amongst others i do refer to this.

It's yet another few plies of search that are dependant upon a simple static evaluation and avoid the backtracking to correct the evaluation.

It is wrong to call this minor, as when you're getting outsearched, you're dead meat, and the dead meat is even more dead if its evaluation that's already wrong in this position, adds another ply of total search reduction, by means of increasing the reduction factor.

Nullmove is that powerful especially because it reduces also positional lines, it's not just a tactical form of search.

What rybka is doing there is in between not taking a risk and the full blown risk that SF takes there as its reduction factor is in a lookuptable.

The advantage of SF there is that it always profits from a bigger search depth because of it, whereas Rybka has a real worst case there.

In Diep for now i'm not willing to soon increase the R of nullmove and i don't want to reduce more than 1 ply either with reductions.

Note we can mathematically prove that the optimum to reduce is 1 ply.
Vincent

That's a very interesting claim, can you provide more details? I don't know any top program nowadays that limits LMR to a single ply. I am quite sure we would drop a ton of elo points if we did so.
Regarding null move, my point is that there is little to gain by (let's say) reducing the null move by 5 plies instead of 4 if a pawn up. The time saved is just a few percent. Neverthless, it appears to be worth it (since all top programs do it), so it means that the risk is pretty low in practice.
 Display posts from previous: All Posts1 Day7 Days2 Weeks1 Month3 Months6 Months1 Year Oldest FirstNewest First
Subject Author Date/Time
Alcides Schulz Tue Mar 27, 2012 11:55 am
Vincent Diepeveen Tue Mar 27, 2012 12:37 pm
Lucas Braesch Tue Mar 27, 2012 1:03 pm
Edmund Moshammer Tue Mar 27, 2012 1:24 pm
Vincent Diepeveen Tue Mar 27, 2012 4:52 pm
Thomas Petzke Tue Mar 27, 2012 1:28 pm
Larry Kaufman Tue Mar 27, 2012 1:46 pm
Alcides Schulz Tue Mar 27, 2012 2:03 pm
Thomas Petzke Tue Mar 27, 2012 2:42 pm
Vincent Diepeveen Tue Mar 27, 2012 5:11 pm
Larry Kaufman Tue Mar 27, 2012 6:15 pm
Vincent Diepeveen Tue Mar 27, 2012 6:22 pm
Larry Kaufman Tue Mar 27, 2012 6:31 pm
Vincent Diepeveen Tue Mar 27, 2012 6:43 pm
Re: When does a cut-node became an all-node? Larry Kaufman Tue Mar 27, 2012 7:17 pm
Vincent Diepeveen Wed Mar 28, 2012 8:00 am
Larry Kaufman Wed Mar 28, 2012 2:08 pm
Vincent Diepeveen Wed Mar 28, 2012 5:07 pm
Larry Kaufman Wed Mar 28, 2012 5:55 pm
Vincent Diepeveen Wed Mar 28, 2012 8:33 pm
Larry Kaufman Wed Mar 28, 2012 9:16 pm
Vincent Diepeveen Wed Mar 28, 2012 9:37 pm
Ed Schroder Thu Mar 29, 2012 3:22 pm
Vincent Diepeveen Wed Mar 28, 2012 8:56 pm
Larry Kaufman Wed Mar 28, 2012 9:26 pm
Vincent Diepeveen Wed Mar 28, 2012 9:59 pm
Vincent Diepeveen Wed Mar 28, 2012 10:02 pm
Larry Kaufman Wed Mar 28, 2012 10:46 pm
Ricardo Barreira Wed Mar 28, 2012 8:57 pm
Vincent Diepeveen Wed Mar 28, 2012 9:22 pm
Ricardo Barreira Thu Mar 29, 2012 9:38 am
Vincent Diepeveen Thu Mar 29, 2012 9:45 am
Marco Costalba Tue Mar 27, 2012 6:37 pm
Robert Hyatt Tue Mar 27, 2012 5:19 pm
Vincent Diepeveen Tue Mar 27, 2012 5:35 pm
Steve Maughan Tue Mar 27, 2012 5:59 pm
Robert Hyatt Tue Mar 27, 2012 5:12 pm
Alcides Schulz Tue Mar 27, 2012 5:41 pm
Robert Hyatt Wed Mar 28, 2012 10:01 pm
Larry Kaufman Wed Mar 28, 2012 10:31 pm
Daniel Shawul Thu Mar 29, 2012 12:28 am
Larry Kaufman Thu Mar 29, 2012 1:51 am
Sam Hamilton Thu Mar 29, 2012 2:05 am
Larry Kaufman Thu Mar 29, 2012 2:37 am
Sam Hamilton Thu Mar 29, 2012 2:56 am
Vincent Diepeveen Thu Mar 29, 2012 9:36 am
Ed Schroder Thu Mar 29, 2012 4:01 pm
Daniel Shawul Thu Mar 29, 2012 10:53 am
Larry Kaufman Thu Mar 29, 2012 2:24 pm
Daniel Shawul Thu Mar 29, 2012 4:04 pm
Daniel Shawul Thu Mar 29, 2012 4:27 pm
Larry Kaufman Thu Mar 29, 2012 5:49 pm
Daniel Shawul Thu Mar 29, 2012 7:18 pm
Larry Kaufman Thu Mar 29, 2012 4:28 pm
Daniel Shawul Thu Mar 29, 2012 4:52 pm
Larry Kaufman Thu Mar 29, 2012 5:58 pm
Daniel Shawul Thu Mar 29, 2012 7:13 pm
Karlo Bala Jr. Thu Mar 29, 2012 8:39 pm
Daniel Shawul Thu Mar 29, 2012 9:02 pm
Karlo Bala Jr. Thu Mar 29, 2012 9:23 pm
Daniel Shawul Thu Mar 29, 2012 9:45 pm
Vincent Diepeveen Fri Mar 30, 2012 12:26 am
Robert Hyatt Thu Mar 29, 2012 8:34 pm
Alcides Schulz Thu Mar 29, 2012 3:05 am
Thomas Petzke Thu Mar 29, 2012 6:53 am

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