Author: Uri Blass
Date: 23:42:26 07/25/01
Go up one level in this thread
On July 25, 2001 at 21:22:05, Uri Blass wrote:
>On July 25, 2001 at 16:59:56, Heiner Marxen wrote:
>
>>On July 24, 2001 at 13:25:39, Uri Blass wrote:
>>
>>>On July 24, 2001 at 09:48:29, Ian Kennedy wrote:
>>>
>>>>In a recent test game against my computer (which was Black), the following
>>>>postion arose:
>>>>
>>>>[D] 4Nr2/2QR1pkp/4p1p1/8/1p6/r3q1NP/6PK/8 b - - 0 0
>>>>
>>>>I'd gone for a cheapo draw attempt hoping to fool it into playing Rxe8. No such
>>>>luck, it played Kh8 and went on to win.
>>>>
>>>>When I went back to the position after 31. ... Rxe8 to see if there was a draw
>>>>to be had, I was surprised to find its a very forced win for White. But neither
>>>>Crafty or Fritz can see the mate all in one go, even though this line I worked
>>>>out in Fritz has 15 checks out of 20 moves before the final mate:
>>>>
>>>>(31... Rxe8?? 32. Rxf7+ Kh6 33. Rxh7+ Kg5 34. h4+ Kg4
>>>>35. Qc4+ Qf4 36. Qe2+ Rf3 37. gxf3+ Qxf3 38. Qe1 Qf4 39. Qd1+ Qf3 40. Qg1 Qf4
>>>>41. Qg2 Qf3 42. Qh3+ Kf4 43. Rf7+ Ke5 44. Rxf3 Kd6 45. Rd3+ Kc6 46. Qg2+ Kc7
>>>>47. Qc2+ Kb8 48. Qc5 Rf8 49. Qxb4+ Kc7 50. Qc5+ Kb7 51. Rd7+ Ka6 52. Ra7# {
>>>>(Fritz 5)})
>>>>
>>>>Yet Crafty on my PC is only showing +3.65 after an hour or so. Maybe there is
>>>>some inaccuracy in the above variation?
>>>
>>>The first move for black that is not obviously forced is 38...Qf4
>>
>>Yes, I agree.
>>
>>>Here are some non trivial mate to find before you can claim mate in 21
>>>
>>>1)After 38...e5
>>>2)After 38...g5
>>>3)After 38...Rc8
>>>4)After 40...Rd8
>>>5)After 40...Re7
>>>6)After 44...Re7
>>>7)After 45...Ke7
>>>
>>>I do not know if there is a forced mate in 21 but you have to work in order to
>>>prove it by a tree and check every legal move of black in every position in
>>>order to see if the computer find a forced mate after it.
>>>
>>>Uri
>>
>>I did investigate this position a bit more. I started with crafty 18.10
>>before 38.Qe1. I did forget to enable EGTBs, and are not sure how much
>>difference that would have made (I have only the 4-piece EGTBs). Anyhow...
>>
>>Crafty v18.10
>>
>>White(1): ponder off
>>pondering disabled.
>>White(1): hash 192M
>>hash table memory = 192M bytes.
>>White(1): setboard 4r3/7R/4p1p1/8/1p4kP/5qN1/4Q2K/8 w - -
>>
>> +---+---+---+---+---+---+---+---+
>> 8 | | | | | *R| | | |
>> +---+---+---+---+---+---+---+---+
>> 7 | | | | | | | | R |
>> +---+---+---+---+---+---+---+---+
>> 6 | | | | | *P| | *P| |
>> +---+---+---+---+---+---+---+---+
>> 5 | | | | | | | | |
>> +---+---+---+---+---+---+---+---+
>> 4 | | *P| | | | | *K| P |
>> +---+---+---+---+---+---+---+---+
>> 3 | | | | | | *Q| N | |
>> +---+---+---+---+---+---+---+---+
>> 2 | | | | | Q | | | K |
>> +---+---+---+---+---+---+---+---+
>> 1 | | | | | | | | |
>> +---+---+---+---+---+---+---+---+
>> a b c d e f g h
>>
>>White(1): st 600
>>search time set to 600.00.
>>White(1): go
>> clearing hash tables
>> time surplus 0.00 time limit 10:00 (10:00)
>> nss depth time score variation (1)
>> 7 1.03 ++ 1. Qe1!!
>> 7-> 1.47 2.63 1. Qe1 Qf4 2. Rb7 e5 3. Rxb4 e4
>> 8 2.30 2.73 1. Qe1 Qf4 2. h5 g5 3. Rb7 e5 4. h6
>> Re6
>> 8-> 2.76 2.73 1. Qe1 Qf4 2. h5 g5 3. Rb7 e5 4. h6
>> Re6
>> 9 5.66 ++ 1. Qe1!!
>> 9-> 8.80 3.12 1. Qe1 Qf4 2. h5 g5 3. Rb7 e5 4. h6
>> Re6
>> 10 12.88 3.32 1. Qe1 Qf4 2. h5 Kg5 3. Rg7 Kh4 4.
>> Rxg6 b3 5. h6 e5
>> 10-> 15.48 3.32 1. Qe1 Qf4 2. h5 Kg5 3. Rg7 Kh4 4.
>> Rxg6 b3 5. h6 e5
>> 11 26.03 ++ 1. Qe1!!
>> 11 1:30 4.16 1. Qe1 Qf4 2. h5 Kg5 3. Kg2 gxh5 4.
>> Rg7+ Kh6 5. Nxh5 Re7 6. Nxf4 Rxg7+
>> 7. Kf3
>> 11-> 1:37 4.16 1. Qe1 Qf4 2. h5 Kg5 3. Kg2 gxh5 4.
>> Rg7+ Kh6 5. Nxh5 Re7 6. Nxf4 Rxg7+
>> 7. Kf3
>> 12 1:59 4.30 1. Qe1 Qf4 2. h5 Kg5 3. Kg2 Rf8 4.
>> Qxe6 Qf3+ 5. Kh2 Qd3 6. Qe7+ Kg4 7.
>> Qxf8 Qxg3+ 8. Kh1 Qe1+ 9. Kh2 gxh5
>> 12-> 2:20 4.30 1. Qe1 Qf4 2. h5 Kg5 3. Kg2 Rf8 4.
>> Qxe6 Qf3+ 5. Kh2 Qd3 6. Qe7+ Kg4 7.
>> Qxf8 Qxg3+ 8. Kh1 Qe1+ 9. Kh2 gxh5
>> 13 3:49 ++ 1. Qe1!!
>> 13 6:07 4.70 1. Qe1 Qf4 2. h5 Kg5 3. Kg2 Rf8 4.
>> Qxe6 Qf3+ 5. Kh2 b3 6. hxg6 Rf6 7.
>> Ne4+ Kxg6 8. Nxf6 Qxf6
>> 13-> 7:05 4.70 1. Qe1 Qf4 2. h5 Kg5 3. Kg2 Rf8 4.
>> Qxe6 Qf3+ 5. Kh2 b3 6. hxg6 Rf6 7.
>> Ne4+ Kxg6 8. Nxf6 Qxf6
>> time=10:00 cpu=98% mat=1 n=183310432 fh=93% nps=305k
>> ext-> chk=20376026 cap=407860 pp=527915 1rep=1291452 mate=29595
>> predicted=0 nodes=183310432 evals=38692257
>> endgame tablebase-> probes done=0 successful=0
>>
>>Obviously, crafty also likes Qe1 and thinks white is winning. But its PV
>>deviates alredy in the second white move from your analysis.
>>So I gave it more time and let it run over night:
>>
>>Black(1): st 43200
>>search time set to 43200.00.
>>Black(1): setboard 4r3/7R/4p1p1/8/1p4kP/5qN1/4Q2K/8 w - -
>>
>> +---+---+---+---+---+---+---+---+
>> 8 | | | | | *R| | | |
>> +---+---+---+---+---+---+---+---+
>> 7 | | | | | | | | R |
>> +---+---+---+---+---+---+---+---+
>> 6 | | | | | *P| | *P| |
>> +---+---+---+---+---+---+---+---+
>> 5 | | | | | | | | |
>> +---+---+---+---+---+---+---+---+
>> 4 | | *P| | | | | *K| P |
>> +---+---+---+---+---+---+---+---+
>> 3 | | | | | | *Q| N | |
>> +---+---+---+---+---+---+---+---+
>> 2 | | | | | Q | | | K |
>> +---+---+---+---+---+---+---+---+
>> 1 | | | | | | | | |
>> +---+---+---+---+---+---+---+---+
>> a b c d e f g h
>>
>>White(1): go
>>crafty is behind 1.5 on time, reducing by 1/3.
>> time surplus 0.00 time limit 720:00 (720:00)
>> nss depth time score variation (1)
>> 10-> 0.40 4.70 1. Qe1 Qf4 2. h5 <HT>
>> 11 0.40 4.70 1. Qe1 Qf4 2. h5 <HT>
>> 11-> 1.29 4.70 1. Qe1 Qf4 2. h5 <HT>
>> 12 1.29 4.70 1. Qe1 Qf4 2. h5 <HT>
>> 12-> 6.15 4.70 1. Qe1 Qf4 2. h5 <HT>
>> 13 6.16 4.70 1. Qe1 Qf4 2. h5 <HT>
>> 13-> 32.96 4.70 1. Qe1 Qf4 2. h5 <HT>
>> 14 28:28 ++ 1. Qe1!!
>> 14 178:14 7.14 1. Qe1 Qf4 2. Qd1+ Qf3 3. Qg1 Qf4 4.
>> Qg2 e5 5. Qh3+ Kf3 6. Qf1+ Ke3 7. Qe2+
>> Kd4 8. Rd7+ Kc5 9. Qc2+ Kb6 10. Qxg6+
>> Ka5 11. Rd5+ Ka4 12. Qxe8+ Ka3 13.
>> Qa8+ Kb2 14. h5
>> 14-> 183:31 7.14 1. Qe1 Qf4 2. Qd1+ Qf3 3. Qg1 Qf4 4.
>> Qg2 e5 5. Qh3+ Kf3 6. Qf1+ Ke3 7. Qe2+
>> Kd4 8. Rd7+ Kc5 9. Qc2+ Kb6 10. Qxg6+
>> Ka5 11. Rd5+ Ka4 12. Qxe8+ Ka3 13.
>> Qa8+ Kb2 14. h5
>> 15 203:23 ++ 1. Qe1!!
>> 15 370:43 9.25 1. Qe1 Qf4 2. Qd1+ Qf3 3. Qg1 Qf4 4.
>> Qg2 b3 5. Rg7 Kxh4 6. Rxg6 Qg4 7. Rh6+
>> Kg5 8. Qd2+ Qf4 9. Rh5+ Kg6 10. Qxf4
>> Re7 11. Qe5
>> 15-> 381:24 9.25 1. Qe1 Qf4 2. Qd1+ Qf3 3. Qg1 Qf4 4.
>> Qg2 b3 5. Rg7 Kxh4 6. Rxg6 Qg4 7. Rh6+
>> Kg5 8. Qd2+ Qf4 9. Rh5+ Kg6 10. Qxf4
>> Re7 11. Qe5
>> 16 443:28 ++ 1. Qe1!!
>> time=720:00 cpu=98% mat=1 n=1909505130 fh=0% nps=44k
>> ext-> chk=-2060764322 cap=13731413 pp=33182471 1rep=154509366
>>mate=1272643
>> predicted=0 nodes=1909505130 evals=837289426
>> endgame tablebase-> probes done=0 successful=0
>>
>>(some counters did wrap multiply)
>>
>>Crafty replaces your 41...Qf3 with 4...b3.
>>After crafty's move we have [D]4r3/7R/4p1p1/8/5qkP/1p4N1/6QK/8 w - -
>>and Chest finds a mate in 10:
>>
>>PV: Rg7 Qf3 Rxg6+ Kf4 Qb2 Qxg3+ Rxg3 Rg8 Qd2+ Ke4 Rxg8 e5 Rg3 Kf5 Qd6 b2 Qg6+
>>Kf4 Qg4#
>>(37 minutes on a K7/600 with 350 MB hash)
>>
>>If black plays Kxh4 instead of Qf3 after the initial Rg7, the mate is one
>>move shorter:
>>[D]4r3/6R1/4p1p1/8/5q1k/1p4N1/6QK/8 w - -
>>PV: Rxg6 Qg4 Qf2 Rf8 Rh6+ Kg5 Qxf8 Qf3 Ne4+ Kg4 Rg6+ Kh4 Qe7+ Qf6 Qh7#
>>(32 seconds)
>>
>>I haven't analysed 41...Qf3, sorry.
>>
>>Regards,
>>Heiner
>
>Chessmaster6000 says only mate in 12 after 41...Qf3.
>
>The main line begins with 42.Qh3+ Kf4 43.Rf7+ Ke5 44.Rxf3 Rd8 45.Re3+
>
>Uri
I believe that after 41...Qf3+
42.Qh3+ is mate in 11 because Chessmaster can see mate in 9 after
42.Qh3+ Kf4 43.Rf7+ Ke5 if I give it some minutes.
Uri
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