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Subject: Re: How long does it take your engine to find the mate in 4?

Author: Brian Katz

Date: 05:50:11 01/01/04

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On December 31, 2003 at 13:15:31, Stan Arts wrote:

>Hello
>
>Neurosis 1.6 on a P3-550 with 48MB hash.
>
>Legal moves: 57   Static score: -264
>Ply Score Time     Nodes      Best move and expected line
>------------------------------------------------------------
>2   -12   5        2828       Bxd7+ Qxd7 Rf8+ Rxf8 Rxf8+ Kxf8
>3   95    11       3788       Bxd7+ Qxd7 Rf8+ Rxf8 Rxf8+ Kxf8 Qxd7
>4   95    66       47029      Bxd7+ Qxd7 Rf8+ Rxf8 Rxf8+ Kxf8 Qxd7
>5   95    297      225882     Bxd7+ Qxd7 Rf8+ Rxf8 Rxf8+ Kxf8 Qxd7
>5   96    362      285154     Re1 < + > Qb8 cxd3 Qe5 Rf8+
>5   357   395      322339     Re1 < + > Qa5 Bxd7+ Kd8 Qxe7+
>5   437   417      340859     Re1 Qb6+ Qxb6 axb6 Re1xe7+ Kd8 Rxd7+ Ke8 cxd3
>5   438   730      602556     Kh1 < + > g5 Rxh7 Rg8 Bxd7+
>5   694   769      634206     Kh1 < + > a6 Rxg7 Qa5 Rxe7+
>5   9993  818      672432     Kh1 <M4> a6 Rxg7 Rf8 Rxf8+ Kxf8 Qf7+
>6   9993  1554     1255045    Kh1 <M4> a6 Rxg7 Rf8 Rxf8+ Kxf8 Qf7+
>7   9993  3059     2421708    Kh1 <M4> a6 Rxg7 Rf8 Rxf8+ Kxf8 Qf7+
>Total nodes:4310286 n/sec:78468  (Q-nodes:94453 max depth:15)
>
>Happy new year,
>Stan
>
>
>>[D]r2qk2r/pp1nbRpp/4Q3/1B6/8/3p4/PPP3PP/5RK1 w kq - 0 17
>>
>>I came across this position in a blitz game tonight and missed the mate (playing
>>Rxg7 instead).  My engine (Bogo) takes a full a minute to see the mate:
>>
>>ply |   score |    time |     nodes |    qnodes | line
>>  1 |   -1.20 |    0.00 |        63 |       120 | cxd3
>>  2+|   -0.70 |    0.01 |       211 |      2770 | Re1
>>  2 |   -0.18 |    0.00 |       294 |      3582 | Re1 dxc2
>>  3+|    0.32 |    0.02 |      1382 |      6644 | Re1
>>  3 |    1.12 |    0.01 |      2015 |      8505 | Re1 d2 Qxe7+ Qxe7
>>  4 |    1.12 |    0.02 |      2574 |     11943 | Re1 d2 Qxe7+ Qxe7
>>  5+|    1.62 |    0.10 |     12127 |     29661 | Re1
>>  5 |    4.99 |    0.16 |     27376 |     57157 | Re1 Qb6+ Qxb6 axb6 Rexe7+
>>                                                  Kd8 Rxd7+ Kc8
>>  6 |    4.99 |    0.11 |     39122 |     80765 | Re1 Qb6+ Qxb6 axb6 Rexe7+
>>                                                  Kd8 Rxd7+ Kc8
>>  7 |    5.36 |    1.68 |    227701 |    386042 | Re1 Qb6+ Qxb6 axb6 Rexe7+
>>                                                  Kd8 Rxd7+ Kc8 Rc7+ Kd8 Rfd7+
>>                                                  Ke8
>>  8 |    5.36 |    1.21 |    373651 |    620391 | Re1 Qb6+ Qxb6 axb6 Rexe7+
>>                                                  Kd8 Rxd7+ Kc8 Rc7+ Kd8 Rfd7+
>>                                                  Ke8
>>  9+|    5.86 |   15.05 |   2168181 |   3291189 | Kh1
>>  9 |   Mat 4 |   41.57 |   7808070 |  11246013 | Kh1 dxc2 Rxg7 Rf8 Rxf8+
>>                                                  Kxf8 Qf7#


Interesting find.
Fritz 8 only finds mate in 4 in the Deep Analysis Mode...Depth Mode but not in
the Total Time or Time in the Deep Analysis mode, where it finds mate in 6 and
ends search, and the same with the infinite analysis mode.

Yace doesn't find it in the Deep Analyis but does in the infinite analysis mode,
nor does Ruffian.

What is also interesting is that in the infinite analysis mode, allowing only 1
variation for white, (if more than one variation are allowed, the search will
take longer)
(This is done by using the minus button in the Engine Pane, depressing it until
only one line at a time can be looked at, otherwise the engine will show
alternative variations which don't show mate or a win. It may even show bad
moves for white at the bottom of the analysis as options as well, depending on
how many alternative line you allow.
That can be done by depressing the Plus button. Each time you press the Plus
button, another line of analysis will be added. Each line of analysis will be
numbered from 1 on up to however many you allow. Using the MINUS button will
bring the variations down. Bring them down until only the number 1 appears next
to your LINES of analysis. There will eventually become MANY lines with the
Number 1 next to it.

These engines find mate in 4 as below:
Yace Paderborn: 4 seconds
Ruffian 1.0.1 : 2 seconds
Ruffian 1.0.0 : 2 seconds
Fritz 5.32    : 0 seconds

Brian



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