OpenChess

Here's a new, and hopefully better, version of DiscoCheck. Probably about +20 ELO compared to DiscoCheck 4.1.

Contempt option added. The default value of 25cp has the good property of significantly reducing the draw rate, while not losing any elo. Thanks to contempt, DiscoCheck will avoid draws and would rather fight to the death than accept a 3-repetition draw in a +/- equal position.

UCI stop command implemented. This means that infinite analysis is finally possible, as well as stopping the engine while it's searching in game play.

No skill level yet, but the recommend way to do that is to limit the number of nodes searched. Now even small values will never crash. For example, you can try 256 nodes, 512 nodes, 1024 nodes, etc. until you find the suitable strength opponent for you.

https://github.com/lucasart/chess
* source code in 'src' folder
* compiles for Linux and Windows (64-bit, SSE 4.2) in the 'bin' folder

Enjoy!

Actually GitHub tries to view executable files when you click on them, instead of offering to download them. You have to click on the 'Raw' button. Otherwise, here are some direct download links to the executables:

• Linux: https://github.com/lucasart/chess/raw/m ... ocheck_4.2
• Windows: https://github.com/lucasart/chess/raw/m ... ck_4.2.exe

I've posted some SSE3 compiles now, so anyone with SSE >= 3 can run those:

• Linux: https://github.com/lucasart/chess/raw/m ... k_4.2_sse3
• Windows: https://github.com/lucasart/chess/raw/m ... 2_sse3.exe

I also suffixed the "normal" compiles with sse4.2, in order to clarify:

• Linux: https://github.com/lucasart/chess/raw/m ... 4.2_sse4.2
• Windows: https://github.com/lucasart/chess/raw/m ... sse4.2.exe

Of course SSE 4.2 is preferred when the CPU can support it (it runs 8% faster on my i7-3770k).

PS: 64-bit only.

I am curious about the origin of the name DiscoCheck. What is the derivation from?
The 'Check' part makes sense for a chess engine, but the Disco bit has me a little bit puzzled.

disco-check is chess slang for "discovered check". Up to version 3.4, it was called DoubleCheck, but I eventually switched to DiscoCheck, because in reality the only checks that are treated differently by the search are discovered checks, not double checks (which is a small subset).

Also, I found the name DiscoCheck amusing, because it rimes with Discotheque: just a ridiculous name so as to not take one's self to seriously with pretentious names (and there are lots of those out there, like Predator, Shredder, Chess Master etc.)

I like stupid names, and I think it's a great idea to call an engine something completely stupid unrelated to chess. I realized that when Fruit came out. Seriously, that was a good one! Everyone was asking: why Fruit ? What's that name got to do with chess ? And Fabien was like... why not ? do you prefer Palm Tree or Skate Board ?

I like the engine and the logo.
I like the name too, why not have a little fun now and then?