Author: Uri Blass
Date: 01:26:04 11/28/01
Go up one level in this thread
On November 27, 2001 at 21:21:08, Heiner Marxen wrote: >In reply to: http://www.icdchess.com/forums/1/message.shtml?196199 >Posted by Mike Hood on November 08, 2001 at 06:12:44: > >[The original message is not accessible anymore] > >[D]2k5/3P4/8/8/8/8/1r5p/R3K3 b Q - > >This is a KRPKRP position, suspected to be a mate in 18. >I have downloaded some 5-piece Nalimov tables for this, namely: >krpkr >krnkr >krbkr >krrkr >kqrkr >i.e. krkr plus an arbitrary further piece. >I had already all the 4-piece tables. >The total amount of my EGTB files now is around 296 MB. > >Then I have asked Chest (current development version 3.23) to solve the >mate in 18. It was intended as a stress test for EGTBs. >It turned out to be a quite massive computation: more than 15 days. >This happened on my K7/600 with 350 MB hash, and additional 40 MB cache >for the EGTBs (I have 512 MB real memory, and run Linux). > >Chest confirms that 1.Kd8 is a mate in 18, and there is no other way to >achieve that: > >PV: Kd8 Ra8+ Kxd7 Ra7+ Kd6 Ra6+ Kd5 Ra5+ Ke4 Rh5 h1=Q+ Rxh1 Rb1+ Kd2 Rxh1 Kc3 >Rc1+ Kb4 Kd5 Kb3 Rc4 Ka3 Kc5 Kb3 Kb5 Ka3 Rb4 Ka2 Ka4 Ka1 Kb3 Kb1 Rc4 Ka1 Rc1# > >Here is the solution tree, 9 moves deep (without duals): > > Kd8 Ra8+ Kxd7 Ra7+ Kd6 Ra6+ Kd5 Ra5+ Ke4 ...+13 > Rh6 h1=Q+ ...+13 > Rf6 h1=Q+ ...+2 > Rd6+ Kxd6 ...+1 > Rg6 h1=Q+ ...+1 > -*- h1=Q# > Rh7 h1=Q+ Rxh1 Rb1+ ...+13 > Rf7 h1=Q+ Rf1 Qe4+ ...+1 > Rd7+ Kxd7 =*= h1=Q# > Rg7 h1=Q+ Rg1 Qxg1# > -*- h1=Q# > Rh8 h1=Q+ Rxh1 Rb1+ =*= Rxh1 ...+13 > Rf8 h1=Q+ Rf1 Qe4+ Kd1 Qb1# > Rd8+ Kxd8 =*= h1=Q# > Rg8 h1=Q+ Rg1 Qxg1# > -*- h1=Q# > O-O-O Rg2 Kb1 Rg1 Kc1 Rxd1+ Kxd1 h1=Q+ ...+8 > -*- h1=Q ...+4 > Kc2 h1=Q Rxg1 Qxg1 ...+8 > Kd2 Qh2+ ...+5 > Kd3 Qf3+ ...+5 > Rd2 Rg3 ...+5 > Rd3 Rc1+ ...+5 > Rd4 Rc1+ ...+5 > Kb1 Qe4+ ...+4 > Kb2 Rg2+ ...+4 > Kb3 Rxd1 ...+4 > Kc1 Rxd1+ ...+4 > Kc3 Rxd1 ...+4 > Re1 Rxe1 ...+4 > Rf1 Rxf1 ...+4 > Rd5 Qxd5 ...+3 > -*- Qe4+ ...+5 > Rc1 Rxc1+ Kxc1 h1=Q+ ...+8 > -*- h1=Q ...+3 > Rxg1 hxg1Q+ Kc2 Qe1 ...+7 > Ka2 Qb6 ...+6 > Kb2 Qd1 ...+6 > Ka1 Rxd1+ Ka2 Rd2+ ...+4 > Kb2 h1=Q ...+4 > Ka2 Rxd1 Ka3 Rb1 ...+2 > -*- h1=Q ...+4 > Kb2 Rxd1 Ka2 Rd2+ ...+4 > Ka3 Rb1 ...+2 > -*- h1=Q ...+4 > Re1 Rxe1+ =*= h1=Q ...+4 > Rf1 Rxf1+ =*= Rf3 ...+3 > Re1 Rg1 Kd1 Rxe1+ Kxe1 h1=Q+ ...+8 > -*- h1=Q ...+4 > Kd2 h1=Q Rxg1 Qxg1 ...+8 > Re5 Qh2+ ...+7 > Re8+ Kxd7 ...+7 > Re2 Qd5+ ...+6 > Re3 Qd5+ ...+6 > Re6 Qd5+ ...+6 > Kc3 Qf3+ ...+5 > Ke3 Rxe1+ ...+5 > Rb1 Rxb1 ...+5 > Rd1 Qh2+ ...+5 > Re7 Kxe7 ...+5 > Kc1 Rxe1+ ...+4 > Kc2 Rxe1 ...+4 > Ke2 Rxe1+ ...+4 > Re4 Qxe4 ...+4 > Rf1 Rxf1 ...+4 > Kd1 Qf3+ ...+3 > -*- Qd5+ ...+5 > Rd1 Rxd1+ Kxd1 h1=Q+ ...+8 > -*- h1=Q ...+4 > Rxg1 hxg1Q+ Kc2 Qe1 ...+7 > Kd2 Kxd7 ...+7 > Kb2 Qd1 ...+6 > Kc2 Rxe1 Kd3 h1=Q ...+5 > Kb3 Rc1 ...+4 > Kc3 Re4 ...+4 > -*- h1=Q ...+4 > Kb1 Rxe1+ =*= h1=Q ...+4 > Kb2 Rxe1 Kb3 Rc1 ...+4 > Kc3 Re4 ...+4 > Ka3 Rb1 ...+2 > -*- h1=Q ...+4 > Rf1 Rxf1+ =*= Rf3 ...+3 > Rf1 Rg1 Rd1 Rxd1+ Kxd1 h1=Q+ ...+8 > -*- h1=Q ...+4 > Rxg1 hxg1Q+ Kc2 Qe1 ...+7 > Kd2 Kxd7 ...+7 > Kb2 Qd1 ...+6 > Kb2 Rxf1 Kc3 Rf3+ ...+5 > Kb3 Rc1 ...+4 > Ka3 Rb1 ...+2 > -*- Rf3 ...+3 > Kc2 Rxf1 Kc3 Rf3+ ...+5 > Kd3 Rf3+ ...+5 > Kb3 Rc1 ...+4 > -*- Rf3 ...+3 > Kd2 Rxf1 Ke3 h1=Q ...+5 > Ke2 h1=Q ...+4 > Kc2 Rf3 ...+3 > -*- Rf3+ ...+5 > Kd1 Rxf1+ Ke2 h1=Q ...+4 > -*- Rf3 ...+3 > Re1 Rxe1+ =*= h1=Q ...+4 > Kb1 Rxf1+ =*= Rf3 ...+3 > Rh1 Rg1+ Rxg1 hxg1Q+ Kc2 Qe1 ...+7 > Kd2 Kxd7 ...+7 > Kb2 Qd1 ...+6 > Kb2 Rxh1 Kc2 Rg1 ...+5 > Kc3 Rg1 ...+5 > Ka3 Rb1 ...+2 > -*- Rc1 ...+4 > Kc2 Rxh1 Kb3 Rc1 ...+4 > -*- Rg1 ...+5 > Kd2 Rxh1 =*= Rg1 ...+5 > Rd2 h1=Q+ Kc2 Rg3 Kb2 Qf3 ...+4 > Re2 Qf3 ...+4 > Rf2 Qe4+ ...+4 > Rd3 Qe4 ...+3 > Rd5 Qxd5 ...+2 > Rg2 Qxg2+ ...+2 > Rh2 Qxh2+ ...+1 > -*- Qh7+ ...+4 > Kb2 Rxd2+ Kb3 Qc1 ...+2 > Kc3 Qc1+ ...+2 > Ka3 Qb1 ...+1 > Rd1 Qh6+ Kb1 Qb6+ ...+1 > Rd2 Qxd2+ ...+1 > Rg1 hxg1Q# > -*- h1=Q+ Rd1 Qh6+ Kb1 Qb6+ ...+1 > Rd2 Qxd2+ ...+1 > -*- h1=Q# > >Total Time (user) = 1337207.05 sec (22286.8 min) (371.4 hrs) (15.5 days) > >From the refutation table... > >refu 1: Kd8 Ra8+ [ 16-] >solu 4: Ra8+ [ 17+] >solu 5: Rc1 [ 1+] >solu 6: Ra7 [ 1+] >solu 7: Rd1 [ 1+] >solu 8: Ra3 [ 1+] >solu 9: Ra4 [ 1+] >solu 10: Ra5 [ 1+] >solu 11: Ra6 [ 1+] >solu 12: Kf1 [ 1+] >solu 13: Kd1 [ 1+] >solu 14: O-O-O [ 12+] >solu 15: Rb1 [ 1+] >solu 16: Ra2 [ 1+] >refu 2: Kb8 d8=Q+ [ 17-] >refu 3: Kc7 d8=Q+ [ 17-] >refu 4: Kb7 d8=N+ [ 17-] >solu 1: d8=Q [ 1+] >refu 5: Kxd7 O-O-O+ [ 63-] >solu 2: Rd1+ [ 6+] >solu 3: Ra7+ [ 16+] > >... we see, that 1.Kxd7 does not succeed in 63 moves, i.e. does not win at all. >Well, that is a direct EGTB hit. > >Quite interesting (and unexpected) is, what part of the analysis took most >of the time. 99.9961% of the time were spent on 1.Kb7 d8=N+ ... wow! bad order of moves I believe that it may be better to use some short search to find the best move based on only material evaluation. You are going to find that 0-0-0+ is better than d8N proving that white has a forced mate by 0-0-0(you do not need to find the shortest mate for this purpose) is doable in a few minutes and it means that chest can replace 99.9961% of the time by few minutes and solve the problem in few minutes after you improve the program. Another possible test for chest may be to find the shortest mate for white after Kb7?? or to find mate for black after Kb7?? d8N+?? I also suspect that using more tablebases like the kqrkn could help. Uri
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