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Subject: Re: Bratko-Kopec

Author: Robert Hyatt

Date: 08:11:08 01/18/98

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On January 17, 1998 at 23:39:02, Bruce Moreland wrote:

>
>On January 17, 1998 at 18:29:35, Robert Hyatt wrote:
>
>>Some of the Bratko-Kopec positions were like this, but there were a few
>>that I disagreed with, Kmoch be damned.  :)  But they were nice in that
>>deeper searches wouldn't help if you didn't understand the particular
>>pawn structure nuance they were targeting...
>
>The problem I had with some of the BK problems wasn't that the problems
>had incorrect solutions, but rather that programs would find answers for
>superficial reasons.  For instance, position 4, which is from Spielmann
>vs Walter, 1928:
>
>rnbqkb1r/p3pppp/1p6/2ppP3/3N4/2P5/PPP1QPPP/R1B1KB1R w KQkq - 0 1
>
>The key is 1. e6, is meant to be a sacrifice.  The reply 1. ... fxe6 is
>crushed by 2. Qh5+, but there is nothing in the test that ensures that
>programs understand the consequences of 1. ... fxe6.
>
>I bet many of the programs tested by BK over the years would not have
>played 2. Qh5+.  Here is this position:
>
>rnbqkb1r/p3p1pp/1p2p3/2pp4/3N4/2P5/PPP1QPPP/R1B1KB1R w KQkq - 0 2
>
>How long does it take your favorite program to find 2. Qh5+ here?


about 45 seconds on the P6... but the score goes from .24 for
Nex6 to .25 for Qh5+... :)

at depth=11 Qh5 fails high.  So 13 plies from the original
position...  to get a *real* result and not a positional
one...  the score after 11 plies is +1.6  fail hi takes about
a minute.  It also fails high again at depth=11...


>
>Imagine how far beyond *any* micro this was in 1980 or so, but there
>they all are, getting full credit for this problem, they all found 1.
>e6.
>
>My favorite BK problem is #22:
>
>2r2rk1/1bqnbpp1/1p1ppn1p/pP6/N1P1P3/P2B1N1P/1B2QPP1/R2R2K1 b - - 0 1
>
>The key is 1. ... Bxe4.  This was a very good recapture extension
>problem in its day, but now you'll probably find it in a second or two.
>
>bruce



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