Chess engines

Not quite... chess.com prohibits you from using engines to help you with rated games in progress. Most serious players analyze their games with an engine after they finish. Heck, chess.com even offers that as a feature to premium members!

That's not true, Arno Nickel famously beat Hydra in a correspondence match. By today's standards Hydra is old. Anyone with Rybka 3 and a fast computer could beat it. Hydra was all about brute force a lot of muscle and not enough brain.

 my understanding is chess.com offers it to non paying members aslo, just that premium members may get more games analyses and at a higher level of analysis also.

• Basic/Free: 1 Computer Analysis per week / search depth of 8 ply estimated at 2000 strength.
• Silver/Gold: 2 Computer Analysis per week / search depth of 10 ply estimated at 2200 strength.
• Platinum/Diamond: 25 Computer Analysis per week / search depth of 12 ply estimated at 2400 strength.

Okay thank you

not just premium! basic gets 1/week

Neat, so they do. :)

Hello.  

After a game, computer analysis could prove to be a useful learning tool.

How does one access the chess.com computer analysis function?

after you finish a game, there will be an analysis function to the right of the screen.

does anyone know the meaning of the + and - numbers in the analysis? I figure that they're there to assess the quality of the move, but what are the numbers in terms of? Meaning..., what would be the highest and lowest number, and what moves would they indicate?

They are in units of pawns, usually from white's perspective. (So -1.0 would mean that black is one pawn ahead.)

They don't really assess the quality of the move, but rather the quality of the position. To get a rough idea about the quality of a move you should look at the difference between the score before and after the move. This should usually be close to zero for the best possible move.

What you said is quite correct but the part  accented in red needs some explanation.

You want a move that pushes the score as far as possible toward your valence, positive for white negative for black. So, if you're White, and the last position evaluation was 0.00 and then after your move the evaluation is +5.00, well, you just made a move that's as good as winning a rook. Buuut, in general the engine would actually have spotted the 'rook winning move' long before you did, and it was already reflected in the evaluation. So, in general, when the evaluation moves a lot, it's cuz you missed your best move, and the large evaluation change was in the wrong direction! (that happens rather too often!) ... so yes, good moves are typically only incrementally positive, and quite close to net zero... but certainly it is possible and desirable for the score to move a lot in your direction on your move from time to time.  

BTW. This has been mentioned, but it's worth repeating -- There are some engine GUIs which evaluate +- with whoever is on the  move as the side which wants + (so it switches each 1/2 move... this is insanely confusing and awful. It's become universal IMO to discuss evaluations in terms of centipawns 0.00 with fixed positve white negative black... there's always a setting on the GUI somewhere that will let you switch the  evaluation form to that standard.) 

Thank you for the information. This tool should help all who use it improve their level of chess. I shall give it a try after the conclusion of my next game. Thanks again.

Appreciate the quick reply guys, now it all makes sense =)

Actually, after a Platinum membership Computer Analysis, Chess.com now shows that it was done at Elo "~2500".

If you own the latest version of Rybka, would you like to have an unrated six-game match against Sigma Chess HIARCS 12.1 MP? I'm running it on a 2.2 GHz Dual Core MacBook on which it supposedly runs at Elo 2950. I'm just curious as to how much better Rybka is, especially since they apparently have very different styles.

I would like to thank all who have posted this wealth of information. The original post was out of curiosity and now I have the foundation for exploration...again tnx

nimbleswitch, you can get a good idea about the different strength of engines here:

http://www.computerchess.org.uk/ccrl/4040/