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Subject: Re: Pharaon - Aristarch, comments & examples

Author: Uri Blass

Date: 12:00:59 08/11/02

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On August 11, 2002 at 12:51:42, Uri Blass wrote:

>On August 11, 2002 at 12:26:17, Mike S. wrote:
>
>>8m+3s P3/700_MHz Blitzmatch 2002
>>
>>                   123456789012
>>1   Pharaon 2.61   0½110½01½½½1  6.5/12
>>2   Aristarch 4.4  1½001½10½½½0  5.5/12
>>
>>(64 MB hash each, 4-piece tbs., no pondering)
>>
>>http://members.surfeu.at/mscheidl/Aristarch-Pharaon.zip (PGN + CBF)
>>
>>From the first game, where Black had the bishop pair and a passer against rook +
>>knight (the last move was 43...Bh2-c7?):
>>
>>Aristarch 4.4 - Pharaon 2.61 [C80]
>>[D]8/2b5/R3b3/2pk1p2/1pNp2Pp/1P3P1P/4K3/8 w - - 0 44
>>44.g5 +1.63/9 1s - This pawn can't be stopped without loosing a bishop (and the
>>game).
>>
>>I had read it before, but forgot: There's a big book available for download
>>separately, for Aristarch. So it played the match with the two small bookfiles
>>only, which are included in the main zip archive. But except the following
>>example from game no. 4, no severe opening problems were visible in the match:
>>
>>Pharaon 2.61 - Aristarch 4.4 [B40]
>>1.e4 c5 2.Nf3 e6 3.Nc3 Nc6 4.d4 Nf6? first calculated move 5.d5 Na5 6.d6 a6 7.e5
>>Ng8 -1.11
>>[D]r1bqkbnr/1p1p1ppp/p2Pp3/n1p1P3/8/2N2N2/PPP2PPP/R1BQKB1R w KQkq - 0 8
>>
>>Another observation in the same game was the following underpromotion blunder.
>>Meanwhile I've been pointed to Aristarch's for_experts.txt, which mentiones that
>>it doesn't underpromote. Here, the problem is that the opponent underpromotes,
>>which A. couldn't expect:
>>
>>[D]r3r3/4Pk1p/pppB2p1/2pp4/2P3n1/2R5/PP3PPP/4R1K1 b - - 0 24
>>24...Rad8?? 25.exd8N+, and there's no time for Rxe1#.
>>
>>Here's a nice example of Aristarch's skills:
>>
>>Aristarch 4.4 - Pharaon 2.61 [E04]
>>[D]r2bk1r1/1p3ppp/p1b1p3/Bp6/4P3/5BP1/PP3P1P/2RR2K1 w q - 0 19
>>19.Rxc6! Bxa5 [19...bxc6 20.e5 Bxa5 (20...Ke7?? 21.Bb4+ c5 22.Bxc5+ Ke8 23.Bc6
>>Mate!) 21.Bxc6+ returns exchange + pawn] 20.Rcd6, followed by Rd7 etc.
>
>19.Rxc6 is easy to find(movei finds it at depth 7 after
>2 seconds on p850)
>After 19...Bxa5 the move 20.Rcd6(if it is the only move to win)
>is a bigger problem and movei prefers 20.e5 with evaluation of
>0.15 pawns for white at depth 13.
>
>Uri

After 19.Rxc6 Bxa5 20.Rcd6 is not winning because of Rd8 when
Rd7 is impossible so this example only demonstrates pharoan's wealnesses.

Uri



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