Why do we use several Chess Engines ?

Hello !

I just buyed Fritz 13 and installed houdini 1.5 and i was wondering why do people use others engines but Houdini ?

It's considered as being the strongest one, no ?

I know there should be a reason so i'm counting on you to explain me that :)

I think that it makes little or no difference.  The Fritz 13 engine is rated at 3517 (it changes as the program is updated) which is hundreds higher than any human player.  The Houdini 3 (not the older Houdini 1.5a) is alleged to be slightly above other engines, but what difference does it make?  If you look at web sites such as chess2u where they do nothing but play one engine against another, you will find that one engine does not always win every game against other engines.  That means that it depends on the opening book used, the position and the endgame tablebooks as well as the engine strength alone.  It also depends on the length of time and depth given for the engine to work.  Some engines are better at quick moves, others better at deeper ply depth.

In our feeble Elo brackets of under 2000, the difference between any of the top engines is on paper.  If you put a played game into Houdini, Fritz, Stockfish or any other highly rated engine, most of the time you will get the exact same recommended move, and any move given as "better" will only be by a fraction of a pawn if there is a difference - not enough for us to use effectively.

Forget about the engines for anything but post game analysis, and then make sure you understand WHY the move is suggested.  If the move is so deep and so sophisticated that you don't understand it, then you haven't gained anything.

Maybe one would want an engine that's not so strong.

Yes, a good comment.  I think the OP here was looking for a stronger engine, otherwise why install a Houdini variant when Fritz is plenty strong?

But looking down, there are other engines with commendable strengths, such as Crafty which is considered more "human" in its analysis and playing characteristics and others which might emulate more human-like errors.  The old Chessmaster series had different player types that could be chosen to play against, and my Fritz 13 also has an intriguing list of imaginary players that you can play "for fun" such as Assassin, Steam-roller, Fraidy-cat, Desperado, Reckless, Tit-fot-Tat, Patzer, Moron and Careless in addition to all the other features you can modify to create custom opponents.

I don't write chess programs, but I do a bit of reading on them.  One of the problems in "dumbing down" a chess engine is trying to create the human-like oversights and errors that are so random and varied in a human opponent and the lack of artistic creativity.  I've seen comments in chess analysis by GMs who make statements like "a computer move" or "a typical computer resource" when analyzing their own games.

I'm perfectly happy with my old Fritz 8 (I think - might be 9). That's strong enough to show me where I blundered and recommend better moves when I review my games against humans, which is what I bought it for.