What Strelka tells about Rybka's nodecount and depth

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ernest
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What Strelka tells about Rybka's nodecount and depth

Post by ernest » Mon Jul 09, 2007 3:10 pm

We get a confirmation that

Rybka nodecount = "real nodecount" divided by 10 to 20
(reverse analysis performed on Rybka by John L. Jerz found: divided by 14)

Rybka depth = "real depth" minus 2


Using for instance test #2 from Michael Gurevich's WM-Test(100):
r1q2rk1/p2bb2p/1p1p2p1/2pPp2n/2P1PpP1/3B1P2/PP2QR1P/R1B2NK1 b - -

Engine: Rybka 1.0 Beta 32-bit (256 MB) by Vasik Rajlich
8.00 0:00 +0.23 1...Nf6 2.Nd2 Qc7 3.b3 Kg7 (55.808) 191
9.00 0:00 +0.25 1...Nf6 2.Nd2 Qc7 3.b3 a5 4.Bb2 (76.032) 207
10.00 0:00 +0.23 1...Nf6 2.Nd2 Kg7 3.b3 Qa6 4.Bb2 Ne8 (126.848) 218
11.01 0:01 +0.26 1...Nf6 2.Nd2 a5 3.Nb1 Nxg4 4.fxg4 Bxg4 5.Rf3 Bh5 6.Nd2 (234.277) 228
12.01 0:02 +0.23 1...Nf6 2.Nd2 a5 3.a4 Qc7 4.b3 Kg7 5.Bb2 Ng8 (567.133) 233
13.01 0:04 +0.21 1...Nf6 2.Nd2 Kg7 3.b3 Qa6 4.Bb2 Qa5 5.Rff1 a6 6.a3 (1.036.076) 237
13.02 0:05 +0.73 1...Bxg4 2.fxg4 f3 3.Qd1 Qxg4+ 4.Kh1 Bh4 5.Rc2 Qh3 6.Bh6 (1.276.837) 224
14.01 0:07 +0.78 1...Bxg4 2.fxg4 f3 3.Qc2 Qxg4+ 4.Kh1 Bh4 5.Bh6 Bxf2 6.Qxf2 (1.518.522) 220
15.01 0:11 +0.90 1...Bxg4 2.fxg4 f3 3.Qd1 Qxg4+ 4.Kh1 Bh4 5.Rc2 Qh3 6.a3 (2.259.528) 225
best move: Bd7xg4 time: 0:29.640 min n/s: 202.752 nodes: 5.677.056

Engine: Strelka 1.8 UCI (256 MB) by Jury Osipov
10.00 0:00 +0.25 1...Nf6 2.Nd2 Qa6 3.Nb3 Ba4 4.Qd1 b5 5.g5 Nh5 6.cxb5 Bxb5 (493.065) 1853
11.35 0:00 +0.25 1...Nf6 2.Nd2 Qc7 3.b3 a5 4.Bb2 a4 5.Rff1 axb3 6.axb3 Kg7 7.g5 (748.970) 1844
12.35 0:00 +0.21 1...Nf6 2.Nd2 Qc7 3.b3 a5 4.Bb2 a4 5.Rff1 Kg7 6.g5 Nh5 7.Qg2 axb3 8.axb3 (1.204.763) 1792
13.35 0:01 +0.26 1...Nf6 2.Nd2 a5 3.Nb1 Nxg4 4.fxg4 Bxg4 5.Rf3 Bh5 6.Nd2 Qd7 7.b3 a4 8.Ba3 Bxf3 9.Nxf3 axb3 10.axb3 (2.058.031) 1829
14.35 0:02 +0.24 1...Nf6 2.Nd2 a5 3.a4 Qc7 4.b3 Kg7 5.Rf1 h6 6.Bb2 Rh8 7.Bc3 h5 8.g5 (4.559.434) 1870
15.35 0:05 +0.73 1...Bxg4 2.fxg4 f3 3.Qd1 Qxg4+ 4.Kh1 Bh4 5.Rc2 Qh3 6.Bh6 Rf6 7.Qd2 Nf4 8.Bxf4 exf4 9.Qc3 Re8 10.Re1 (11.734.770) 1981
16.35 0:07 +0.91 1...Bxg4 2.fxg4 f3 3.Qd1 Qxg4+ 4.Kh1 Bh4 5.Rc2 Qh3 6.a4 Nf4 7.Bxf4 exf4 8.Ra3 Rae8 9.a5 bxa5 10.Rxa5 Rf7 (14.525.551) 1999
17.35 0:08 +0.93 1...Bxg4 2.fxg4 f3 3.Qd1 Qxg4+ 4.Kh1 Bh4 5.Rc2 Qh3 6.a4 Nf4 7.Bxf4 exf4 8.Ra3 Rae8 9.a5 Rf7 10.axb6 axb6 11.Rd2 Bf6 (18.240.777) 2037
18.35 0:27 +1.25 1...Bxg4 2.fxg4 f3 3.Qc2 Qxg4+ 4.Kh1 Bh4 5.Bh6 Rf7 6.h3 Qxh3+ 7.Rh2 Qg4 8.Bd2 Raf8 9.Qd1 Bg3 10.Ne3 Qd7 11.Rxh5 gxh5 (56.260.524) 2062
best move: Bd7xg4 time: 0:33.609 min n/s: 2.090.260 nodes: 70.251.553

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mclane
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Re: What Strelka tells about Rybka's nodecount and depth

Post by mclane » Mon Jul 09, 2007 3:17 pm

what is the intention to divide the NPS ? or to change the search-depth into something else.
that sounds very strange to me.

the only explanation i would have is , that somebody does not want to be related with someone else' program.

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Werner
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Re: What Strelka tells about Rybka's nodecount and depth

Post by Werner » Mon Jul 09, 2007 4:57 pm

ernest wrote:We get a confirmation that

Rybka nodecount = "real nodecount" divided by 10 to 20
(reverse analysis performed on Rybka by John L. Jerz found: divided by 14)

Rybka depth = "real depth" minus 2


Using for instance test #2 from Michael Gurevich's WM-Test(100):
r1q2rk1/p2bb2p/1p1p2p1/2pPp2n/2P1PpP1/3B1P2/PP2QR1P/R1B2NK1 b - -

13.02 0:05 +0.73 1...Bxg4 2.fxg4 f3 3.Qd1 Qxg4+ 4.Kh1 Bh4 5.Rc2 Qh3 6.Bh6 (1.276.837) 224


Engine: Strelka 1.8 UCI (256 MB) by Jury Osipov

15.35 0:05 +0.73 1...Bxg4 2.fxg4 f3 3.Qd1 Qxg4+ 4.Kh1 Bh4 5.Rc2 Qh3 6.Bh6 Rf6 7.Qd2 Nf4 8.Bxf4 exf4 9.Qc3 Re8 10.Re1 (11.734.770) 1981
Hi Ernest,
please show me how to compare the nodecounts in this example:
1.276.837 -> 11.734.770
Werner

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tiger
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Re: What Strelka tells about Rybka's nodecount and depth

Post by tiger » Tue Jul 10, 2007 2:15 am

From what I have seen with my experiences on Rybka 1.0 beta:

real depth = Rybka depth + 3.

This way, the author of Rybka can hide the end of the PV so static evaluations cannot be associated with positions (the evaluation of a line is the static evaluation of the last position in the line). This makes understanding how the program evaluates positions more difficult.

Dividing the number of positions searched by a large value (10 to 20) can be done in order to have people believe that your program is "slow" (has a low node per second value), which is generally popular. It also make it harder to understand the search algorithm.

Now assuming that you can create a "clone" of Rybka, why not use different masquerading values, like display a depth that is 2 less than the real depth and divide the number of position searched by some random value between 10 and 20?


// Christophe

Gandalf

Re: What Strelka tells about Rybka's nodecount and depth

Post by Gandalf » Tue Jul 10, 2007 4:25 am

tiger wrote:From what I have seen with my experiences on Rybka 1.0 beta:

real depth = Rybka depth + 3.
No, looking at the Rybka 1.0 Beta executable you can see that the instruction at 0040d7c9 subtracts 2 from the depth before sending it to output.

ernest
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Re: What Strelka tells about Rybka's nodecount and depth

Post by ernest » Tue Jul 10, 2007 11:28 am

Werner wrote: Hi Ernest,
please show me how to compare the nodecounts in this example:
1.276.837 -> 11.734.770
Hi Werner,
You are right here (factor is x9), but looking at more examples on the WM-Test (#1, #3, ...) you find factors from x8 to x25

By the way, Jerz's paper (not so easy to read...) is
http://mysite.verizon.net/vzesz4a6/current/id18.html

Of course all this has to take in account that Strelka is only "partly" :) a clone of Rybka 1.0 Beta.

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tiger
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Re: What Strelka tells about Rybka's nodecount and depth

Post by tiger » Tue Jul 10, 2007 5:25 pm

ernest wrote:
Werner wrote: Hi Ernest,
please show me how to compare the nodecounts in this example:
1.276.837 -> 11.734.770
Hi Werner,
You are right here (factor is x9), but looking at more examples on the WM-Test (#1, #3, ...) you find factors from x8 to x25

By the way, Jerz's paper (not so easy to read...) is
http://mysite.verizon.net/vzesz4a6/current/id18.html

Of course all this has to take in account that Strelka is only "partly" :) a clone of Rybka 1.0 Beta.

In this paper you can see in the disassembled code that Vas subtract 3 from the real ply depth before it prints it. There is a comment in the assembler listing so it is easy to find. Actually he apparently count plies with a half ply counter (this allows for 0.5 ply extensions), so this value is first divided by 2, then 3 is subtracted from it.

This confirms that

Rybka's depth = real ply depth - 3

and

Strelka's depth = real ply depth - 1



// Christophe

Gandalf

Re: What Strelka tells about Rybka's nodecount and depth

Post by Gandalf » Wed Jul 11, 2007 2:37 am

The article talks about Rybka 1.2f, while you mentioned that this was the case with Rybka 1.0 Beta. It seems they do two different things.

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tiger
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Re: What Strelka tells about Rybka's nodecount and depth

Post by tiger » Wed Jul 11, 2007 7:21 am

Gandalf wrote:The article talks about Rybka 1.2f, while you mentioned that this was the case with Rybka 1.0 Beta. It seems they do two different things.

The 3 plies difference comes from my experience by looking at the output of the program (Rybka 1.0 beta) and letting it play against mine at fixed depth.


// Christophe

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Dr.Wael Deeb
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Re: What Strelka tells about Rybka's nodecount and depth

Post by Dr.Wael Deeb » Wed Jul 11, 2007 2:31 pm

tiger wrote:
Gandalf wrote:The article talks about Rybka 1.2f, while you mentioned that this was the case with Rybka 1.0 Beta. It seems they do two different things.

The 3 plies difference comes from my experience by looking at the output of the program (Rybka 1.0 beta) and letting it play against mine at fixed depth.


// Christophe
It's all clear now,it's a Rybka clone almost....
_No one can hit as hard as life.But it ain’t about how hard you can hit.It’s about how hard you can get hit and keep moving forward.How much you can take and keep moving forward….

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