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Subject: Re: More from Chrilly about Hydra - Wait a minute!

Author: Kolss

Date: 01:23:07 06/07/05

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On June 07, 2005 at 02:09:56, Uri Blass wrote:

>2)I do not believe that hydra's hardware give hydra advantage that is equivalent
>to being  more than 10 times faster.


Hello Uri,

At the last IPCCC (Feb. 2005) I had the (dubious?!) pleasure to play Hydra (the
16-way version) with Ikarus. Ikarus was running on a Centrino 2.0 GHz which is
approximately equivalent in terms of speed to an "Athlon 3800+". We (i.e.
Chrilly, Christopher (Lutz) and I) discovered that Hydra plies seemed to be more
or less equal to Ikarus plies with respect to what is seen (i.e. tactical
horizon). Hydra was reaching three, sometimes four more plies than Ikarus:
Ikarus would play a move that Hydra had not expected, Hydra's evaluation would
jump up, and Ikarus would need one more move to see that it had been bad; or
Hydra would expect a move with a good score (for itself, of course), Ikarus
would "plan" something different with OK evaluation, then after two or three
minutes it would fail low, see what was wrong and eventually change to the move
expected by Hydra; in gereral, Ikarus would more or less show the evaluation
that Hydra had had two moves earlier in the game.

Three to four plies (very) roughly translates into a factor of 20 (+- perhaps 5)
with an average effective braching factor. Since that tournament, Hydra has been
updated to 32 processors with new FPGA cards, which developers claim make it two
(or was it five?!) times faster yet.

In total, that makes for a speed advantage of about a factor 40. With a quad
opteron, you may get it down to 10...

That should be about 250 Elo points difference in strength (150 if you get the
quad), just hardware-wise, which makes it really an uphill fight. That does not
mean good programs are completely chanceless, of course - there were two
programs that managed to draw Hydra at the IPCCC - but odds are clearly against
you.

Best regards - Munjong.



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