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Subject: Re: Try to solve mate.

Author: Heiner Marxen

Date: 13:58:23 09/14/02

Go up one level in this thread


On September 14, 2002 at 10:44:49, leonid wrote:

>On September 14, 2002 at 10:14:52, Paul wrote:
>
>>On September 14, 2002 at 09:47:21, leonid wrote:
>>
>>>On September 14, 2002 at 09:26:25, leonid wrote:
>>>
>>>>On September 14, 2002 at 08:51:31, Paul wrote:
>>>>
>>>>>On September 14, 2002 at 07:55:35, leonid wrote:
>>>>>
>>>>>>Hi,
>>>>>>
>>>>>>This mate is easy and only 9 moves deep:
>>>>>>
>>>>>>[D]bqRNNkqr/Q7/qPnPqBqN/Q4q2/5Qr1/5q2/5nQ1/bQqQqBKR w - -
>>>>>
>>>>>Hi Leonid,
>>>>>
>>>>>Pretz (p3/1000) also finds this one easy, it gets this in 3 seconds:
>>>>>
>>>>>00:03 WM9 06 Nxe6+ Qgxe6 Be7+ Nxe7 dxe7+ Qxe7 Qaxf5+ Bf6 Nxf6+ Qaxc8 Nh7+ Ke8
>>>>>Qxg6+ Rxg6 Qgxg6+ Qf7 Qaxf7#

Chest (Athlon 1500+, 128MB hash) confirms this in 56.21 secs:

PV: Nxe6+ Qgxe6 Bg7+ Bxg7 Qbxf5+ Bf6 Nxf6+ Qaxc8 Nh7+ Ke8 d7+ Kd8 dxc8=Q+ Kxc8
Qfc7+ Qxc7 Qxc7#

 Nxe6+ Qgxe6 Bg7+ Bxg7 Qbxf5+ ...+6
                  Qxg7 Qbxf5+ ...+3
       Qexe6 Be7+ =*=  dxe7+  ...+5
       Qfxe6 Bg7#

It is so easy/fast, because black has mating resources, too, like Rxg2#.

>>>>>>Still, maybe, You will be tempted for something more heavy and I this way will
>>>>>>be able to find more on this position:
>>>>>>
>>>>>>[D]2qRQq2/p6P/q1BqqR1N/r6B/n1QNQQ1B/r6k/b1QKNP1q/bq4qn w - -
>>>>>>
>>>>>>On description of this mate I can see that it was solved by selective in 13
>>>>>>moves but brute force search went not up to the end in order to find shortest
>>>>>>move. Brute force search, without finding any mate, went only 9 moves deep.
>>>>>
>>>>>This one was indeed a lot more difficult, mine didn't fare so well here:
>>>>>
>>>>>06:49 WM11 07 Q8xe6+ Qdxe6 Qff3+ Rxf3 Qxf3+ Kxh4 Nhf5+ Rxf5 Nxf5+ ...
>>>>>
>>>>>So it found a mate in 11 in almost 7 minutes, with an incomplete pv ... these
>>>>>d#*&#@rned hashtables ;) ... will have to think about this ... any tips anyone?
>>>>>
>>>>>>Please indicate Your result.
>>>>>>
>>>>>>Thanks,
>>>>>>Leonid.
>>>>>
>>>>>Thanks for your mates as usual ...
>>>>
>>>>Thanks, Paul!
>>>>
>>>>Now I can see that second one is no far then 11 moves. I  can even put this
>>>>position at 10 moves by brute force for night. If braching factor will not
>>>>suddenly jump, then it should be enough time for me for finding its depth.
>>>>
>>>>First position have excellent time!
>>>>
>>>>Mine, on usual setting, found mate in 1.75 sec.
>>>>
>>>>Cheers,
>>>>Leonid.
>>>
>>>Paul, just after writing my message, I started to see second position in my file
>>>to indicate 11 moves. When I finally found it (I not indicate before on what
>>>page I had it), I looked that it was in reality solved by selected in 11 moves,
>>>just as You said. Before upper part of page was covered with page keeper and it
>>>is how I missed some additional description. If I knew this yesterday, when I
>>>found this position, I could put search for 10 moves by brute force at night.
>>
>>Hey!! ... so you tricked us ... that's not fair ... I would have found it much
>>faster if I'd known! ... just kiddin' ... :)
>
>I was actually tricked by myself. I did expected that this position was very
>difficult since I could see that it was solved by very slow selective and only
>at 13 moves. 13 moves at large default setting (I use it before searching by
>much easier solution) took 13.5 minutes to solve. When I looked into 11 moves
>selective solution its paramether indicated that solution was almost simple.
>
>
>>>Selective in 11 moves was solved in 18 seconds. Usual setting.
>>
>>Not bad at all ... you really should implement hash to get a bit faster though
>>... ;)

Chest is still running for depth 11, but after 3478 secs has already reported
that there is no mate in 10.  So, we are already sure, that 11 is minimal
depth.

#  4      0.09s                17kN [ 10.28]  1.07        737-         0
#  5      0.96s [ 10.67]      137kN [  7.88]  1.21       8654-         0
#  6      6.32s [  6.58]      791kN [  5.79]  1.49      66512-         0
#  7     31.30s [  4.95]     3675kN [  4.65]  2.11     351756-         0
#  8    143.98s [  4.60]    16349kN [  4.45]  2.73    1718242-      7352
#  9    668.36s [  4.64]    73337kN [  4.49]  3.46    8452143-   5252957
# 10   3477.74s [  5.20]   373030kN [  5.09]  4.02   45004182-  41804949

Cheers,
Heiner


>I do expect that one day I will come back to my programming. At least, this last
>week I had plaintly of work and it could be that needed second computer will be
>not that long to wait for. Still 64 bits gadget will be ideal to start with. I
>am sure that when new, 64 bits, computer will arrive chatting of people here
>will be very animated. Too many things to redo, or write from scratch.
>
>Cheers,
>Leonid.
>
>>>Cheers,
>>>Leonid.
>>
>>Groetjes,
>>Paul



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