Mate in 2, not found

[Rebel]

Code: Select all

ProDeo:
   1	00:00	          22	22.000	-8,78	Nc8-d6 c7xd6 Ka1xa2
   1	00:00	          93	93.000	-7,52	Ka1-b2
   1	00:00	         119	119.000	-6,16	Ka1xa2
   2	00:00	         155	155.000	 0,00	Ka1xa2
   3	00:00	         383	383.000	 0,00	Ka1xa2
   3	00:00	         891	891.000	 0,00	Be7-a3
   3	00:00	         894	894.000	 0,00	Be7-a3
   3	00:00	         914	914.000	  +M2	Be7-a3 Kg7xf6 Ba3-b2+
 

REBEL-EAS

Code: Select all

 49/49	00:32	  21.102.822	653.540	 0,00	Ka1xa2
 50/50	00:35	  23.541.257	654.541	 0,00	Ka1xa2
 51/51	00:43	  28.304.798	657.501	 0,00	Ka1xa2

Stopped after 8 minutes

[petero2]

In my case (texel) the problem is also null move pruning. I do have null move verification in texel at depth >= 10. However, storing the null move search result in the transposition table made verification ineffective, at least for this position. The problem was that during verification search a shallower search from a previous iteration, where verification search was not used, was found in the transposition table, so the verification search was terminated early with wrong result.

The fix is to not store null move search results in the transposition table. This fix does not seem to affect elo enough to be measurable by 30000 games.

[chessica]

Many thanks, your compile is working.

But I can't compile it.

[chessica]

[d]n1N3br/2p1Bpkr/1pP2R1b/pP3Pp1/P5P1/1P1p4/p2P4/K7 w - - 0 1 ChessDotCpp:

Code: Select all

 1/3	00:00,002	 192	96k	-5,90	Ka1-b2
 1/3	00:00,001	 157	157k	-5,23	Sc8-a7
 1/3	00:00,001	 125	125k	-5,03	b3-b4
 1/3	00:00,001	 64	64k	-4,94	Le7-d8
 1/3	00:00,001	 29	29k	-4,17	Ka1xa2
---------------------------------------------------------------------------
 2/3	00:00,002	 315	158k	-4,72	Ka1-b2 a2-a1D+ Kb2xa1
 2	00:00,002	 290	145k	 0,00	Sc8-a7
 2/3	00:00,002	 275	138k	-4,31	b3-b4 a5xb4
 2/3	00:00,002	 250	125k	-4,21	Le7-d8 Kg7-f8
 2/3	00:00,002	 225	113k	 0,00	Ka1xa2
---------------------------------------------------------------------------
 3/5	00:00,003	 448	149k	-4,85	b3-b4 a5xb4 Ka1xa2
 3/3	00:00,003	 414	138k	-4,21	Le7-d8 Kg7-f8 Ka1xa2
 3/5	00:00,003	 392	131k	 0,00	Sc8-a7
 3/1	00:00,003	 361	120k	 0,00	Ka1xa2
 3/3	00:00,003	 344	115k	 0,00	Ka1-b2 a2-a1D+ Kb2xa1
---------------------------------------------------------------------------
 4/4	00:00,005	 656	131k	-4,71	Le7-d8 Kg7-f8 Ka1xa2 Lh6-g7
 4/5	00:00,005	 627	125k	-4,66	b3-b4 a5xb4 Ka1xa2 b4-b3+ Ka2-b2
 4/6	00:00,005	 576	115k	 0,00	Sc8-a7
 4/3	00:00,004	 525	131k	 0,00	Ka1-b2 a2-a1D+ Kb2xa1
 4/5	00:00,004	 498	125k	 0,00	Ka1xa2
---------------------------------------------------------------------------
 5/7	00:00,008	 914	114k	-5,26	Le7-d8 Kg7-f8 Ka1xa2 Lh6-g7 Ld8-e7+ Kf8-e8
 5/3	00:00,006	 759	127k	 0,00	b3-b4 a5xb4 Ka1xa2 b4-b3+ Ka2-b2
 5	00:00,006	 726	121k	 0,00	Sc8-a7
 5/3	00:00,006	 710	118k	 0,00	Ka1-b2 a2-a1D+ Kb2xa1
 5/2	00:00,005	 682	136k	 0,00	Ka1xa2
---------------------------------------------------------------------------
 6/9	00:00,012	 1k	106k	-5,54	Le7-d8 Kg7-f8 Ka1xa2 Lh6-g7 Ld8-e7+ Kf8-e8 Ka2-b1
 6/5	00:00,009	 1k	113k	 0,00	b3-b4 a5xb4 Ka1xa2 b4-b3+ Ka2-b2
 6/2	00:00,008	 985	123k	 0,00	Sc8-a7
 6/3	00:00,008	 968	121k	 0,00	Ka1-b2 a2-a1D+ Kb2xa1
 6/2	00:00,008	 940	118k	 0,00	Ka1xa2
---------------------------------------------------------------------------
 7/11	00:00,022	 2k	108k	-4,69	Sc8-d6 c7xd6 Tf6xd6 f7-f6 Le7xf6+ Kg7-f7 Ka1xa2 Sa8-c7
 7/4	00:00,013	 1k	109k	 0,00	b3-b4 a5xb4 Ka1xa2 b4-b3+ Ka2-b2
 7/2	00:00,013	 1k	106k	 0,00	Sc8-a7
 7/3	00:00,013	 1k	104k	 0,00	Ka1-b2 a2-a1D+ Kb2xa1
 7/4	00:00,013	 1k	102k	 0,00	Ka1xa2
---------------------------------------------------------------------------
 8/11	00:00,029	 3k	105k	-4,17	Sc8-d6 c7xd6 Tf6xd6 f7-f6 Le7xf6+ Kg7-f7 Lf6-e5 Lh6-f8 Td6-d7+ Lf8-e7
 8/14	00:00,028	 3k	102k	 0,00	b3-b4 a5xb4 Ka1xa2 b4-b3+ Ka2-b2
 8/4	00:00,023	 2k	108k	 0,00	Sc8-a7
 8/4	00:00,023	 2k	107k	 0,00	Ka1-b2 a2-a1D+ Kb2xa1
 8/3	00:00,022	 2k	109k	 0,00	Ka1xa2
---------------------------------------------------------------------------
 9/11	00:00,040	 4k	111k	+M2	Le7-a3 Kg7xf6
 9/15	00:00,039	 4k	108k	 0,00	Ka1-b2 a2-a1D+ Kb2xa1
 9/15	00:00,034	 4k	106k	 0,00	b3-b4 a5xb4 Ka1xa2 b4-b3+ Ka2-b2
 9/2	00:00,030	 3k	104k	 0,00	Sc8-a7
 9/4	00:00,030	 3k	103k	 0,00	Ka1xa2
---------------------------------------------------------------------------
 10/6	00:00,044	 5k	108k	 0,00	b3-b4 a5xb4 Ka1xa2 b4-b3+ Ka2-b2
 10/4	00:00,043	 5k	109k	 0,00	Ka1-b2 a2-a1D+ Kb2xa1
 10/5	00:00,042	 5k	110k	 0,00	Sc8-a7
 10/4	00:00,041	 5k	111k	 0,00	Ka1xa2
 10/3	00:00,041	 4k	109k	+M2	Le7-a3 Kg7xf6
---------------------------------------------------------------------------

ELO Value from engine=??

[chessica]

Hi,
I found this position : [d]n1N3br/2p1Bpkr/1pP2R1b/pP3Pp1/P5P1/1P1p4/p2P4/K7 w - - 0 1 I was surprised that even strong programs don't find it.
It seems , at least for me, that its the Late Move Reduction that is the cause.

Any idea ?

Philippe

RobboLito_009:


29/58 00:08,315 10.884k 1.309k 0,00 Ka1xa2