Engines I have lost patience with or become bored with.

[Graham Banks]

Why don't you just use engines which are around your strength at _full_
strength for that purpose? IMO this gives a much better match
than all those dumb down tries.
BTW in your original post you say that the new Junior is stronger
than Stockfish. Actually it is not, by a lot and I am sure it is much more
than 100 rating points below Stockfish.

Guenther

He should try NagaSkaki 5.12. It has some different "personalities" plus you can change some easy to understand parameters in a similar way to what you can do with Chessmaster.

[tano-urayoan]

If you want limit strength then you will have 2 or 3 engines max, forget about the rest. But this limiting strength has not been successful implanted by any engine if I recall correctly.

[tomgdrums]

Why don't you just use engines which are around your strength at _full_
strength for that purpose? IMO this gives a much better match
than all those dumb down tries.
BTW in your original post you say that the new Junior is stronger
than Stockfish. Actually it is not, by a lot and I am sure it is much more
than 100 rating points below Stockfish.

Guenther

I replied to this on the Rybka forum as well and all I know is that Stockfish has a losing record against Junior 2010 on my compouter. In fact Stockfish doesn't fare to well any matches I have tested it in. It is a super strong engine to be sure but right now I don't seeing it as being stronger then Junior 2010. As I continue matches with the two I will of course change my opinion if Stockfish gets the upper hand. I am not trying to start an argument I am just going by wins and losses on my computer.

[mcostalba]

I replied to this on the Rybka forum as well and all I know is that Stockfish has a losing record against Junior 2010 on my compouter. In fact Stockfish doesn't fare to well any matches I have tested it in. It is a super strong engine to be sure but right now I don't seeing it as being stronger then Junior 2010. As I continue matches with the two I will of course change my opinion if Stockfish gets the upper hand. I am not trying to start an argument I am just going by wins and losses on my computer.

Care to post some numbers ? Thanks.

[Michel]

Question.

How does one implement limit strength? I am thinking of implementing this in GnuChess
as it is an often requested feature (and I like it myself very much).

The most obvious thing I can see is

(1) measure the relation of your engine's strength to its nps and put this in a lookup table.
(2) at startup do a quick self test to measure the nps on the current computer.
(3) in the function that gives wall clock time insert a time odds factor equal to the actual nps and the nps corresponding to the desired elo.

Here is what is done in Crafty ( and Pupsi):

Set SkillLevel to a number between 0 and 100.
When returning from the evaluation function do this:

reducedVal = (val * SkillLevel)/100 + Random(100 - SkillLevel)

where Random(x) is a random number between 0 and x.

SkillLevel 0 gives random values
SkillLevel 100 gives full strength.

So the lower the skill level, the more "noise" is added to the evaluation.

Works remarcably well!

Kind regards,
Jesper

Ok thanks. I'll try that.

[tomgdrums]

Here is the first tournament I ran. This is the order in which they finished:

Deep Shredder 12 Kamikaze-Hiarcs Paderborn 2007 MP, Deep Junior 2010, Stockfish 1.5 JA, Zappa Mexico II, and Deep Sjeng WC 2008.

It was round robin in the Shredder 12 GUI with ponder off. I was surprised by the result. I thought Stockfish or Deep Junior would have won. I threw Shredder Kamikaze in there on a lark! Stockfish is a strong engine but it has yet to show clear superiority (in matches and now tournaments) to really anyone. I will post more. This was kind of fun to watch.


1 DShredder 12 Kamikaze X ½ 1 1 1 1 4.5 / 5 8.75 90.00%
2 HIARCS Paderborn 2007 MP ½ X 1 1 0 1 3.5 / 5 7.75 70.00%
3 Deep Junior 2010 win32 UCI 0 0 X 1 1 ½ 2.5 / 5 4.00 50.00%
4 Stockfish 1.5 JA 0 0 0 X 1 1 2.0 / 5 2.50 40.00%
5 Zappa Mexico II 0 1 0 0 X ½ 1.5 / 5 4.00 30.00%
6 Deep Sjeng WC2008 0 0 ½ 0 ½ X 1.0 / 5 2.00 20.00%

[mcostalba]

Here is the first tournament I ran. This is the order in which they finished:

Deep Shredder 12 Kamikaze-Hiarcs Paderborn 2007 MP, Deep Junior 2010, Stockfish 1.5 JA, Zappa Mexico II, and Deep Sjeng WC 2008.

It was round robin in the Shredder 12 GUI with ponder off. I was surprised by the result. I thought Stockfish or Deep Junior would have won. I threw Shredder Kamikaze in there on a lark! Stockfish is a strong engine but it has yet to show clear superiority (in matches and now tournaments) to really anyone. I will post more. This was kind of fun to watch.

December Engine Tourney

• Rank Name DS HI De St Za De Points S-B % Perf
  1 DShredder 12 Kamikaze X ½ 1 1 1 1 4.5 / 5 8.75 90.00%
  2 HIARCS Paderborn 2007 MP ½ X 1 1 0 1 3.5 / 5 7.75 70.00%
  3 Deep Junior 2010 win32 UCI 0 0 X 1 1 ½ 2.5 / 5 4.00 50.00%
  4 Stockfish 1.5 JA 0 0 0 X 1 1 2.0 / 5 2.50 40.00%
  5 Zappa Mexico II 0 1 0 0 X ½ 1.5 / 5 4.00 30.00%
  6 Deep Sjeng WC2008 0 0 ½ 0 ½ X 1.0 / 5 2.00 20.00%

Thanks for posting results. I don't see the time control used, but is only a minor thing.

Anyhow, not to undermine your effort that I appreciate a lot, but I can guarantee you that in a 5 matches per engine tournment result is _almost_ completely random.

You need at least X10 times the number of games (50 games per engine) to start to have something to discuss on.

Just for your information on how engine testing works