To Ronald de Man: recent stockfish_syzygy compiles are fishy

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hgm
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Full name: H G Muller

Re: To Ronald de Man: recent stockfish_syzygy compiles are f

Post by hgm »

phenri wrote:Hello,

I noted that TBhits have decreased considerably in certain positions. Is this normal?

[d]1B1b4/7K/1p6/1k6/8/8/8/8 w - - 0 1

Analysis by Stockfish 200214:
1.Ba7 Bh4 2.Bxb6
= (0.00) Depth: 120/4 00:00:01 6004kN, tb=61234


Analysis by Stockfish 220214:
1.Ba7 Bh4 2.Bxb6 Kxb6
= (0.00) Depth: 120/5 00:00:19 204MN, tb=12
Seems to me absolutely nothing is normal here. The position already is 5-men, so there should never be any need to search deeper than 1 ply, so some 20 nodes. After 1.Ba7 the move bxa7 should come out as best even at 1 ply + QS. The PVs shown at 4 and 5 ply are total bogus.

Perhaps this is a Cylinder Chess version of Stockfish, so that after 1... bxa7 black could play Kh7xa7! 1/2-1/2. :idea:
ZirconiumX
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Re: To Ronald de Man: recent stockfish_syzygy compiles are f

Post by ZirconiumX »

hgm wrote:...a Cylinder Chess version of Stockfish...
Well, if I ever get bored, H.G....

Matthew:out
tu ne cede malis, sed contra audentior ito
syzygy
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Joined: Tue Feb 28, 2012 11:56 pm

Re: To Ronald de Man: recent stockfish_syzygy compiles are f

Post by syzygy »

hgm wrote:
phenri wrote:Hello,

I noted that TBhits have decreased considerably in certain positions. Is this normal?

[d]1B1b4/7K/1p6/1k6/8/8/8/8 w - - 0 1

Analysis by Stockfish 200214:
1.Ba7 Bh4 2.Bxb6
= (0.00) Depth: 120/4 00:00:01 6004kN, tb=61234


Analysis by Stockfish 220214:
1.Ba7 Bh4 2.Bxb6 Kxb6
= (0.00) Depth: 120/5 00:00:19 204MN, tb=12
Seems to me absolutely nothing is normal here. The position already is 5-men, so there should never be any need to search deeper than 1 ply, so some 20 nodes.
tbhits = 12 is normal, white has 12 legal moves. The pv shown is just SF doing a regular search on the "optimal" moves without probing TBs. All by design.

The broken 200214 version failed to detect that the root position was a tablebase position. Now it's fixed. Please simply discard the broken version.
Last edited by syzygy on Sun Feb 23, 2014 7:34 pm, edited 1 time in total.
phenri
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Re: To Ronald de Man: recent stockfish_syzygy compiles are f

Post by phenri »

Thank you

But there is a strange thing, the new version takes much more time to reach depth 120, while the former reaches depth 120 in one second. And so I find contradictory comments in the commit with what I see there.
It is currently unused and only adds
overhead for nothing."
NVM, I actually confused "overhead for nothing." with "overheat for nothing."

Anyway, for me it seems to me that the CPU is running too long for nothing.
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hgm
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Re: To Ronald de Man: recent stockfish_syzygy compiles are f

Post by hgm »

Oh sorry. I was looking at the board in flip-view! :oops:
syzygy
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Re: To Ronald de Man: recent stockfish_syzygy compiles are f

Post by syzygy »

phenri wrote:But there is a strange thing, the new version takes much more time to reach depth 120, while the former reaches depth 120 in one second.
I think you are still comparing with the broken version. See my previous comment. Discard = throw away = delete from your HD. Broken = broken...

I've explained about a hundred times how SF+TB treats (root) positions that are in the tablebases. Use the search function.