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Subject: Re: The usefull-ness of PVS

Author: Robert Hyatt

Date: 08:47:17 01/13/04

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On January 13, 2004 at 10:15:20, Michel Langeveld wrote:

>Just wanted to share a number.
>I tested TSCP with and without PVS.
>
>The difference is : 24.3% - 39.0%
>
>To be precise the TSCP version I used has:
>- killers
>- history killers
>- alfa beta
>- no hashtables
>- no nullmove
>
>Opening position Gothic Chess:
>rnbqckabnr/pppppppppp/10/10/10/10/PPPPPPPPPP/RNBQCKABNR w KQkq -
>
>without PVS
>
>6    215    305037    -10  b1c3 b8c6 i1h3 i8h6 e2e4 e7e5
>7   1575   2511295     18  b1c3 b8c6 i1h3 i8h6 e2e4 e7e5 f2f4
>
>with PVS
>
>6    190    261471    -10  b1c3 b8c6 i1h3 i8h6 e2e4 e7e5
>7   1192   1889545     18  b1c3 b8c6 i1h3 i8h6 e2e4 e7e5 f2f4
>
>boostup of 24.3%
>
>Tactical position in Gothic Chess (38.4%)
>r1q2r2k1/p1p1p3pp/10/5p1p2/2P2P3P/2PC3PK1/P2B1Nc3/1R1Q5R w - -
>
>without PVS
>6    595    903139   -486  i3j3 h5h4 d1j7 i8j7 j3i4 g2h2 i4h4 f8d8 j1d1 d8d3
>d2d3
>7   4065   6253437  -9990  i3j3 h5h4 d1j7 i8j7 j3i4 c8e8 i4i5 g2i2 i5j5 e8h5
>
>with PVS
>6    525    817502   -486  i3j3 h5h4 d1j7 i8j7 j3i4 g2h2 i4h4 f8d8 j1d1 d8d3
>f2d3
>7   2481   3947446  -9990  i3j3 h5h4 d1j7 i8j7 j3i4 c8e8 i4i5 g2i2 i5j5 e8h5
>
>boostup of 39.0%
>
>For the source read next post

That looks pretty normal.  PVS is not a "3x faster" algorithm.  It just shaves
the size of the tree.  25% is a reasonable guess as to how much, and it is
free with no real cost except for occasional re-searches.



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