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Subject: Re: what does "fail high" mean?

Author: Uri Blass

Date: 13:49:14 11/30/02

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On November 30, 2002 at 16:15:08, Scott Gasch wrote:

>On November 29, 2002 at 22:34:40, scott farrell wrote:
>
>>On November 29, 2002 at 21:12:55, Scott Gasch wrote:
>>
>>>On November 29, 2002 at 17:22:20, Will Singleton wrote:
>>>
>>>>2rr3k/1p4p1/1P2b2p/p1Bnpp1q/8/Q1P2PP1/P6P/RB3RK1 b - - 0 26
>>>>
>>>>Solution times (amd 1.6ghz):
>>>>
>>>>Yace       not in 5 min
>>>>Crafty     not in 5 min
>>>>Aristarch  3:48 min
>>>>Gromit     3:12 min
>>>>Ruffian    44 sec
>>>>CM9000     5 sec
>>>>
>>>
>>>Monsoon fails high in 2:16 and resolves a PV in 4:27.
>>>
>>> 1u   +0.35  00:00:00.02  11           PV= a4 <+0.00>
>>> 1u   +1.35  00:00:00.05  57           PV= Nf4 <+0.00>
>>> 1.   +1.35  00:00:00.08  77           PV= Nf4 <+0.00>
>>> 2-   +0.57  00:00:00.13  190          **FL** --
>>> 2u   -0.47  00:00:00.14  302          PV= Ra8 1. Bd3 <+0.00>
>>> 2u   -0.36  00:00:00.15  380          PV= Rc6 1. Qxa5 <-1.00>
>>> 2u   -0.10  00:00:00.16  448          PV= Nf6 1. Qxa5 <-1.00>
>>> 2.   -0.10  00:00:00.21  508          PV= Nf6 1. Qxa5 <-1.00>
>>> 3.   +0.59  00:00:00.27  1635         PV= Nf6 1. Qxa5 e4 <-1.00>
>>> 4u   +0.64  00:00:00.31  6748         PV= Rc6 1. Bd3 Nxb6 2. Bxb6 Rxb6 [Q]
>>>                                        > 3. Qxa5 [Q] <+0.00>
>>> 4.   +0.64  00:00:00.38  9055         PV= Rc6 1. Bd3 Nxb6 2. Bxb6 Rxb6 [Q]
>>>                                        > 3. Qxa5 [Q] <+0.00>
>>> 5+   +1.40  00:00:00.47  22433        Nf6! ++
>>> 5.   +1.49  00:00:00.63  42341        PV= Nf6 1. Bd6 Bc4 2. Re1 Qxf3 3. Bxe5
>>>                                        > [Q] <+0.00>
>>> 6.   +1.52  00:00:00.93  90963        PV= Nf6 1. Bd6 e4 2. fxe4 fxe4 3. Bc2
>>>                                        > <+0.00>
>>> 7.   +1.77  00:00:01.49  209895       PV= Nf6 1. Bc2 Rd2 2. Rf2 Rxf2 3. Bxf2
>>>                                        > Qxf3 4. Qxa5 [Q] <+0.00>
>>> 8.   +1.77  00:00:03.82  698640       PV= Nf6 1. Bc2 Rd2 2. Rf2 Rxf2 3. Bxf2
>>>                                        > Qxf3 4. Qxa5 <+0.00>
>>> 9+   +2.52  00:00:05.36  994464       Nf6! ++
>>> 9.   +2.71  00:00:08.69  1812429      PV= Nf6 1. Bd6 Bc4 2. Rf2 e4 3. g4 Nxg4
>>>                                        > 4. fxg4 Qxg4+ [+] 5. Bg3 Rd1+
>>>                                        > [Q] 6. Kg2 [Q] <-1.00>
>>>10.   +3.02  00:00:26.78  5824368      PV= Nf6 1. Bd6 Bc4 2. Rf2 e4 3. Bc2
>>>                                        > e3 4. Rg2 Qxf3 5. Re1 <+1.00>
>>>11+   +3.77  00:02:16.62  28726569     Nf4! ++
>>>11.   +5.19  00:04:27.40  58248289     PV= Nf4 1. gxf4 Rd2 2. Bf2 [threat]
>>>                                        > Qxf3 3. Qxa5 Bd5 4. Qxd5 [threat]
>>>                                        > Qxd5 5. Bxf5 Rf8 6. c4 Qxc4 [Q]
>>>                                        > <+3.00>
>>
>>How do you guys get this sort of output?
>>
>>My engine doesnt report the final move Nf4 until it has fully analysed that
>>move, and hence already has the PV.
>
>After a complete search of all moves in the root position to (at least) 10 ply
>depth monsoon's PV started with Nf6 (and it printed the 10. line).
>
>Now we begin checking every move in the root position to at least depth 11.  The
>first move analized, of course, is the PV move from last search depth -- Nf6.
>The next move monsoon analized was Nf4.  This move caused a root fail high of
>the aspiration window and caused the 11+ line to be output.  The engine has
>fully analized the Nf6 move at this point but because it caused a root fail high
>the aspiration window must be adjusted and the entire position researched with
>the new window.

In that case it is normal to analyze again Nf6 with a bigger window in order to
get an exaqct score.

Even if you choose not to do it you can give a pv of one move Nf6 at depth 11
before you give a pv of Nf4.

Uri





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