Author: leonid
Date: 04:32:40 01/19/01
Go up one level in this thread
On January 19, 2001 at 07:17:48, Heiner Marxen wrote: >On January 18, 2001 at 22:06:37, leonid wrote: > >>On January 18, 2001 at 19:13:22, Paul wrote: >> >>>On January 18, 2001 at 19:01:08, Pete Galati wrote: >>> >>>>On January 18, 2001 at 18:44:05, leonid wrote: >>>> >>>>>Hi! >>>>> >>>>>If you would like to find a mate here is one position. It is very easy to solve >>>>>but not that simple to find shortest mate. >>>>> >>>>>I failed here even in 3 hours to find shortest mate through brute force search. >>>>>Maybe you will have better chance. >>>>> >>>>> 1k4q1/1pppPr2/PbbP1N1n/QP2rn1R/1q6/1q2RBB1/q1q2PPP/6NK black to go >>>>> >>>>>Leonid. >>>> >>>>Is this the right position? >>>> >>>>[D]1k4q1/1pppPr2/PbbP1N1n/QP2rn1R/1q6/1q2RBB1/q1q2PPP/6NK b - - 0 1 >>> >>>If so, then mine says it's a mate in 10 for black starting with Nxg3+ ... >>>It looks like a daily reverse auction ... Anyone lower, anyone? :) >>> >>>Paul >> >>Position is exact and response 10 moves must be or shortest possible, or very >>close move. Actually my program solved this position through selective search in >>11 moves. Solution was instant. Finding shortest mate is the other story. >>Through brute force program said in 8 mate is not there. Only 9 still could be >>looked. >> >>I found that branching factor was terrible to see 9 moves. AMD 400Mhz. >> >>8 moves - 2h 44 min. >>7 moves - 2 min 48 sec. >>6 moves - 7 sec. >> >>Leonid. > >Chest says "no mate in 9" in 180 sec (3 min) (K7/600 350MB TT) >My branching factor is not that bad (depth, seconds, speed, TT-nodes in-out) ># 1 0.00 0.87 1- 0 ># 2 0.00 1.00 1- 0 ># 3 0.01 0.97 45- 0 ># 4 0.07 1.07 338- 0 ># 5 0.37 1.27 1971- 0 ># 6 1.78 1.66 9653- 0 ># 7 9.25 1.99 52004- 0 ># 8 41.00 2.45 261032- 0 ># 9 180.08 2.97 1253899- 1 > >May be that your move ordering for the defender (here: white) is not >so good. Aggresive defender moves are important to reduce the size >of the search trees. > >You seem to like bizarre positions :-) > >Heiner Good! Now I can try this position with 9 moves. Only if mate was not there that it could take very long time. It could be that move order could be improved but it could be question of position. This position was solved actually not badly by selective search. 10 moves (by mistake I wrote before 11) was solved in less that 0.055 sec. Have no idea about exact time. Could see only zeros. I like heavy and strange positions since they can help in spotting some invisible bug in my program. Mainy for fun but also for practical reason I like to solve sometime few mates. For around 4 years I touched nothing in my mate solver but was working with other parts of program that use the same main brain. Some bug could come there meantime. Leonid.
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