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Up Topic The Rybka Lounge / Test Positions / Zugzwang with a capital Z
- - By Dadi Jonsson (Silver) [is] Date 2010-06-12 21:26
1Q6/8/8/2pK3p/8/5N1q/1P4pp/5Rbk w - -


When this position was posted here on the forum the poster said that it demonstrates why relying on any one engine, even Rybka, isn't the greatest idea.

I analyzed the position with Rybka 4 using IDeA instead of infinite analysis. The result demonstrates two things:

1) The analysis methods you use can be just as important as the engine you choose.

2) IDeA can compensate for some types of engine weaknesses.

It seems to be true that Rybka will not find the solution from the starting position of the study but nevertheless IDeA, using Rybka for the analysis, comes up with a detailed solution ('R' in the notation marks transpositions):
[hl=pgn][Event "?"]
[Site "?"]
[Date "2010.06.12"]
[Round "?"]
[White "?"]
[Black "?"]
[Result "*"]
[FEN "1Q6/8/8/2pK3p/8/5N1q/1P4pp/5Rbk w - - 0 1"]
[SetUp "1"]

1. Qxh2+ Qxh2 2. Rb1 h4 (2... c4 3. Kc6 c3 (3... h4 {R}{+7.00})4. bxc3 h4 5.
Kb7 {R}{+7.00}) 3. Kc6 c4 (3... h3 4. Kb7 c4 {R}{+7.00}) 4. Kb7 h3 (4... c3 5.
bxc3 h3 6. Ka8 {R}{+7.00}) 5. Ka8 c3 6. bxc3 Qb8+ 7. Rxb8 Bc5 (7... Bf2 8. Rh8
g1=N (8... g1=Q 9. Rxh3+ Kg2 10. Nxg1 {+7.00})9. Nxg1 Bxg1 {R}{+7.00} (9...
Kxg1 {+7.00}))(7... Bh2 8. Rh8 g1=Q 9. Nxg1 {+7.00}) 8. Rh8 g1=R (8... g1=N 9.
Nxg1 {R}{+7.00})(8... g1=Q 9. Rxh3+ Kg2 10. Nxg1 {+7.00}) 9. Nxg1 (9. Rxh3+ Kg2
{+7.00}) 9... Bxg1 (9... Kxg1 10. Rxh3 Kf2 11. Rh5 {+7.00}) 10. Rxh3+ Kg2 {+7.
00} *
Parent - - By yanquis1972 (****) [us] Date 2010-06-18 00:24
could you share what settings you used for this? awhile back i gave an admittedly pretty meak effort with my 'default' settings & came up empty.
Parent - - By Dadi Jonsson (Silver) [is] Date 2010-06-18 19:12
I had deleted the project, but I ran it again (I may have used slightly different settings above):

Analysis settings: 30s AND depth 1
Width 10%, FA check 4
Limit White alternatives to 8
Project score bounds -50 to 30000
Percentage of leaf nodes to prolongate: 100%

Running eight Rybka 4 X64 (256MB hash, ASMM, no EGTBs) it took less than an hour to solve this.
Parent - - By yanquis1972 (****) [us] Date 2010-06-22 22:19
do you typically set leaf node prolongation @ 100%? i've never touched this setting -- does it simply, instead of selecting the top 1/5 of the lines to prolongate in that stage as appears to be default, just lengthen them all?
Parent - By Dadi Jonsson (Silver) [is] Date 2010-06-23 08:29

> do you typically set leaf node prolongation @ 100%?


Sometimes I do that, especially when I have many engines analyzing. I also use it when starting a new project.

> does it simply, instead of selecting the top 1/5 of the lines to prolongate in that stage as appears to be default, just lengthen them all?


It extends a greater number of lines, but not necessarily every line. In some cases it means that it will extend lines that would not be extended otherwise.
Up Topic The Rybka Lounge / Test Positions / Zugzwang with a capital Z

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