Author: Uri Blass
Date: 07:55:24 07/23/02
Go up one level in this thread
On July 23, 2002 at 10:33:15, Robert Hyatt wrote: >On July 23, 2002 at 09:41:10, Ed Schröder wrote: > >>On July 22, 2002 at 14:11:23, Robert Hyatt wrote: >> >>>On July 22, 2002 at 11:52:35, Ed Schröder wrote: >>> >>>>The two you entirely miss the point of Kasparov's suspicion, sigh... >>>> >>>>Lesson 61, now pay attention my pupils :) >>>> >>>>[d]r1r1q1k1/6p1/p2b1p1p/1p1PpP2/PPp5/2P4P/R1B2QP1/R5K1 w - - id DEEP BLUE - >>>>Kasparov,G; >>>> >>>>Position before 36.axb5 >>>> >>>>Here DB for a long time showed the following main-line: >>>> >>>>36.Qb6 Qe7 37.axb5 Rab8 38.Qxa6 e4 39.Bxe4 Qe5 40.Bf3 Rcd8 41.Qa7 Qc3 42.Bh5 >>>> >>>>Now let's have a look at the main-line shall we? >>>> >>>>After 39...Qe5 we get: >>>> >>>>[d]1rr3k1/6p1/Q2b1p1p/1P1PqP2/1Pp1B3/2P4P/R5P1/R5K1 w - - >>>> >>>>As you can see black has sacrificed 3 (!!) pawns for a king attack. And this my >>>>pupils is what Kasparov could not believe, a computer sacrificing 3 pawns and so >>>>he started asking questions how that could be. >>>> >>>>The refusal of IBM to answer Kasparov's questions made Kasparov suspicious and >>>>from one thing came another. >>>> >>>>This is *the* heart of the discussion. >>>> >>>>Ed >>> >>> >>>So? If two _current_ programs think axb5 and Qb6 are equal, what do you >>>conclude then? That we all have similar king safety? That we all like >>>the same move (axb5) but for different reasons? >> >>Again, axb5 or Qb6 is irrelevant. What is relevant is the main-line. Black has >>nothing for the 3 pawns. You don't need to be a GM to see that, you don't need >>the complete main-variation, after 39...Qe5 the picture is clear that black has >>nothing for the 3 pawns, see the above diagram. Yet the mainline is a very human >>approach to establish a) a draw by eternal check or b) looking for counter play. > > >Do you think sacrificing the three pawns is the _only_ way to proceed after >axb5? Is fritz showing the same sacrifice in its PV after it gets the same >score for both moves? If so, is fritz getting help too? Remember that >Kasparov did _not_ get to see the partial PV from deep blue. And remember >that we don't know what happens in the last N plies of the PV since we can't >see them. Perhaps it found something different than tossing three pawns, >because I don't believe Fritz would sac three pawns and say "equal to winning >a pawn outright" myself. > > > > >> >>Kasparov *KNEW* about the mainline (just check your records), exactly *THE* >>reason he started to ask questions. > >He knew about what _he_ saw. Not about what DB saw. He knew what fritz >could see after a few minutes. Not about what it could see after weeks of >computing (at that time, since it took almost three days at today's speed to >get the two scores equal). > > >> >>Bob, this is an issue about chess, not computer chess, try to understand 36.Qb6 >>Qe7 37.axb5 Rab8 38.Qxa6 e4 39.Bxe4 Qe5 as a chess player, not as a computer >>chess programmer. > > > >Try to understand why programs are saying axb5 is _just_ as good... which >Fritz did. Crafty got to within .1 after 2.5 days... > > > >> >>I know you entirely want to blacken Kasparov for the public scandal but then you >>should tell history as it happened, here is: >> >>1) Kasparov doesn't understand DB's main-line 36.Qb6 Qe7 37.axb5 Rab8 38.Qxa6 e4 >>39.Bxe4 Qe5 and starts to ask questions how a computer who usually sits on every >>pawn suddenly can sacrifice 3 pawns in a row. > >OK... but two points: (1) kasparov didn't see db's main line. The main line >is incomplete in any case so what happens to the last N plies is anybody's >guess. (2) fritz and Crafty are _both_ saying that axb5 and Qb6 are identical >after several days of searching. That suggests that either fritz and crafty >at DB speeds would produce the _same_ mystery, or there is something else going >on. At least we can prove that his statement is false. The fact that they show the same score does not mean that they are going to choose deeper blue's move because they need to see bigger score for axb5 relative to Qb6 in order to choose axb5. I also believe that deep fritz and crafty of today can see deeper than deeper blue at the same speed thanks to null move pruning. Uri
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