Author: chandler yergin
Date: 17:44:38 04/12/05
Go up one level in this thread
On April 12, 2005 at 18:13:59, John Merlino wrote: >On April 12, 2005 at 15:20:35, chandler yergin wrote: > >>On April 12, 2005 at 11:54:35, John Merlino wrote: >> >>>On April 12, 2005 at 05:15:43, chandler yergin wrote: >>> >>>>On April 12, 2005 at 00:23:30, John Merlino wrote: >>>> >>>>>On April 11, 2005 at 23:36:27, chandler yergin wrote: >>>>> >>>>>>On April 11, 2005 at 13:00:10, Rob Basham wrote: >>>>>> >>>>>>>On April 11, 2005 at 12:24:18, John Merlino wrote: >>>>> >>>>>>>>>New game, >>>>>>>>>[D]2r1r2k/4R1pp/pb6/1p6/2nqN1QB/P5PP/1PB4K/5R2 w - - 0 1 >>>>>>>>> >>>>>>>>>Analysis by Shredder 8: >>> >>><Some Analysis Snipped> >>> >>>>>>>>>1.Bf6 Qxf6 2.Nxf6 Bg1+ 3.Kxg1 Rg8 4.Nxg8 Nxb2 5.Qxg7# >>>>>>>>> +- (#152) Depth: 12/42 00:00:22 7641kN >>>>>>>>>1.Bf6 Rxe7 2.Bxd4 Rd8 3.Qh4 Ree8 4.Nc3 Re2+ 5.Nxe2 h6 6.Kh1 Rxd4 7.Rf8# >>>>>>>>> +- (#152) Depth: 13/18 00:00:23 7840kN >>>>>>>>>1.Bf6 Rxe7 2.Bxd4 Rd8 3.Qh4 Bxd4 4.Qxe7 Rg8 5.Rf8 Bg1+ 6.Kxg1 Nd6 7.Qxd6 b4 >>>>>>>>>8.Rxg8+ Kxg8 9.Qd8+ Kf7 >>>>>>>>> +- (#150) Depth: 14/40 00:00:43 15586kN >>>>>>>>>1.Bf6 Rxe7 2.Bxd4 Rd8 3.Qh4 Bxd4 4.Qxe7 Rg8 5.Rf8 Bc5 6.Nxc5 Nd6 7.Qxd6 b4 >>>>>>>>>8.Rxg8+ Kxg8 9.Qe6+ Kf8 10.Nd7# >>>>>>>>> +- (#150) Depth: 15/36 00:00:43 15751kN >>>>>>>>>1.Bf6 Rxe7 2.Bxd4 Rd8 3.Qh4 h5 4.Qxe7 Ne5 5.Qxe5 Bxd4 6.Qxh5+ Kg8 7.Bb3+ Rd5 >>>>>>>>>8.Bxd5# >>>>>>>>> +- (#150) Depth: 16/38 00:00:47 17089kN >>>>>>>>>1.Bf6 Rxe7 2.Bxd4 Rce8 3.Qf5 Kg8 4.Ng5 g6 5.Qd5+ Re6 6.Rf8+ Kxf8 7.Qf3+ Ke7 >>>>>>>>>8.Qb7+ Bc7 9.Qxc7+ Kf8 10.Qg7# >>>>>>>>> +- (#150) Depth: 17/36 00:00:49 17858kN >>>>>>>>> >>>>>>>>>(, 11.04.2005) >>>>>>>> >>>>>>>>Shredder's output is incredibly bizarre here. The position is a Mate in 9, but >>>>>>>>not a single PV shows mate in 9 moves (although there are mates shown in 10, 7 >>>>>>>>and even 5 moves!??). >>>>>>>> >>>>>>>>Conclusion: Shredder found the best move, but did NOT conclusively find the mate >>>>>>>>in 9. >>>>>> >>>>>>THe Mate in 9 is not forced; Shredder gave all the variations leading to >>>>>>Mate after the Key Move. >>>>>> >>>>>>With "Best PLay" by Black it's Mate in 9. >>>>>> >>>>>>If Black errs.. he gets Mated sooner. >>>>> >>>>>I understand that, but Shredder's output still makes no sense at all. What do >>>>>you mean by "Shredder gave all the variations leading to Mate after the Key >>>>>Move"? >>>> A Program evaluates every possible move at each ply depth; >>>>that is one complete iteration. >>>>Shredder found a Mate at ply 12, another at ply 13, another at ply 14, >>>>another at ply 15, another at play 16 etc. >>>> >>>>What don't you understand? >>> >>>Simple -- take this PV from Shredder (which is the first one listed above): >>> >>>1.Bf6 Qxf6 2.Nxf6 Bg1+ 3.Kxg1 Rg8 4.Nxg8 Nxb2 5.Qxg7# >>> +- (#152) Depth: 12/42 00:00:22 7641kN >>> >>>A program should not announce a Mate for the side to move that is simply not >>>possible with best play. If I were to stop analysis at this point and post my >>>findings here, it would be soundly refuted by the simple fact that there is no >>>Mate in 5 for White. >>> >>>It seems bizarre to me that, at depth 12, the Shredder thinks that there is a >>>forced mate in 5 (only 9 plies away). >>> >>>jm >> The Program did what a Program is supposed to do! >> >>I "clipped" the analysis. >>Do you have any doubt, that if I had let it run,. that it would stabalize >>on the Mate in 9 with a deeper search? > >No, I have no doubt about that at all. But there are two problems with that: > >1) Anybody could say that about any program with regards to a forced mate of >reasonably short distance, and > >2) It's not the ability to find the mate that I have called into question. It is >the PV output that makes no sense. (Notice that I haven't even mentioned the >"#150" that Shredder regularly puts out for no reason....) > >jm That's because you don't have clue what the Program is doing!
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