Thanks guys!
So now that I know what happened I can reconstruct how this happened... this is some kind of tutorial about how to play the losing move...
I was using McCain X (4CPU, 128 MB RAM.) The idea was to play a game at low depth to see how the game would have continued. Then I reach high depth in multiPV=3 to look for alternative moves, and check if that suggest a different move than low depth...
I make it play a move at Depth 28:
28/43 0:01 +0.69 53...gxf4 54.gxf4 Bc4 55.Bc2 Bb5 56.Bxf5 Be2 57.Be6 Bf3 58.Bh3 Be2 59.Bf5 Bf1 60.Be6 Bg2 61.Bg4 Bf1 62.Bh5 Bd3 63.Bd1 Bc4 64.Bf3 Bb3 65.Bh5 Bc2 66.Be2 Bb3 (4.558.130) 3495
And a full Depth=28 game that ends in a draw (because it needs some depth 89 to find 54.exf4!!)
Now it's time to check at a higher depth MultiPV=3, what do I see?
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37 0:01 +0.64 53...gxf4 54.gxf4 Bc4 55.Bc2 Be2 56.Bxf5 Bf1 57.Bg4 Bd3 58.Bd1 Bf1 59.Bb3 Bc4 60.Bc2 Be2 61.Bg6 Bf1 62.a4 b5 63.axb5 Bxb5 64.Bf7 Kd6 65.Kb7 Bd7 66.Bg6 Be6 (7.207.927) 4002
37 0:01 +0.64 53...Be4 54.Ba2 gxf4 55.gxf4 Bf3 56.Bb1 Be2 57.Bxf5 Bf1 58.Bg4 Bd3 59.Bd1 Bf1 60.Bb3 Bc4 61.Bc2 Be2 62.Bg6 Bf1 63.a4 b5 64.axb5 Bxb5 65.Bf7 Kd6 66.Kb7 Bd7 (7.207.927) 4002
37 0:01 +0.88 53...Bc4 54.Bc2 Bf1 55.Bxf5 Be2 56.Bc2 Bf3 57.Bd3 Bg2 58.Ka6 Kc6 59.Bc2 Bf3 60.Ba4+ Kc7 61.Kb5 Be2+ 62.Kb4 Bg4 63.Bb5 Bf3 64.Bf1 Kc6 65.Bd3 Bg4 66.Bb5+ Kb7 (7.207.927) 4002
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38 0:01 +0.64 53...gxf4 54.gxf4 Bc4 55.Bc2 Be2 56.Bxf5 Bf1 57.Bg4 Bd3 58.Bd1 Bf1 59.Bb3 Bc4 60.Bc2 Be2 61.Bg6 Bf1 62.a4 b5 63.axb5 Bxb5 64.Bf7 Kd6 65.Kb7 Bd7 66.Bg6 Be6 (7.588.508) 3991
38 0:01 +0.64 53...Be4 54.Ba2 gxf4 55.gxf4 Bf3 56.Bb1 Be2 57.Bxf5 Bf1 58.Bg4 Bd3 59.Bd1 Bf1 60.Bb3 Bc4 61.Bc2 Be2 62.Bg6 Bf1 63.a4 b5 64.axb5 Bxb5 65.Bf7 Kd6 66.Kb7 Bd7 (7.588.508) 3991
38 0:01 +0.88 53...Bc4 54.Bc2 Bf1 55.Bxf5 Be2 56.Bc2 Bf3 57.Bd3 Bg2 58.Ka6 Bf3 59.Kb5 Bg4 60.Kb4 Kc6 61.Bb5+ Kb7 62.Bf1 Kc7 63.Ba6 Kc6 64.Bd3 Kc7 65.Bg6 Be2 66.Bf5 Bf3 (7.588.508) 3991
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39 0:02 +0.64 53...gxf4 54.gxf4 Bc4 55.Bc2 Be2 56.Bxf5 Bf1 57.Bg4 Bd3 58.Bd1 Bf1 59.Bb3 Bc4 60.Bc2 Be2 61.Bg6 Bf1 62.a4 b5 63.axb5 Bxb5 64.Bf7 Kd6 65.Kb7 Bd7 66.Bg6 Be6 (10.486.067) 4019
39 0:02 +0.64 53...Be4 54.Ba2 gxf4 55.gxf4 Bf3 56.Bb1 Be2 57.Bxf5 Bf1 58.Bg4 Bd3 59.Bd1 Bf1 60.Bb3 Bc4 61.Bc2 Be2 62.Bg6 Bf1 63.a4 b5 64.axb5 Bxb5 65.Bf7 Kd6 66.Kb7 Bd7 (10.486.067) 4019
39 0:02 +0.88 53...Bc4 54.Bc2 Bf1 55.Bxf5 Be2 56.Bc2 Bf3 57.Bd3 Bg2 58.Ka6 Bf3 59.Kb5 Bg4 60.Kb4 Kd6 61.Bb5 Kc7 62.Kc3 Kd6 63.Kd2 Ke6 64.Ba6 Bf3 65.Bd3 Bg4 66.Kc3 Kd6 (10.486.067) 4019
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40 0:02 +0.64 53...gxf4 54.gxf4 Bc4 55.Bc2 Be2 56.Bxf5 Bf1 57.Bg4 Bd3 58.Bd1 Bf1 59.Bb3 Bc4 60.Bc2 Be2 61.Bg6 Bf1 62.a4 b5 63.axb5 Bxb5 64.Bf7 Kd6 65.Kb7 Bd7 66.Bg6 Be6 (11.351.269) 4018
40 0:02 +0.64 53...Be4 54.Ba2 gxf4 55.gxf4 Bf3 56.Bb1 Be2 57.Bxf5 Bf1 58.Bg4 Bd3 59.Bd1 Bf1 60.Bb3 Bc4 61.Bc2 Be2 62.Bg6 Bf1 63.a4 b5 64.axb5 Bxb5 65.Bf7 Kd6 66.Kb7 Bd7 (11.351.269) 4018
40 0:02 +0.88 53...Bc4 54.Bc2 Bf1 55.Bxf5 Be2 56.Bc2 Bf3 57.Bd3 Bg2 58.Ka6 Bf3 59.Kb5 Bg4 60.Kb4 Kd6 61.Bb5 Kc7 62.Kc3 Kd6 63.Kd2 Ke6 64.Ba6 Bf3 65.Bd3 Bg4 66.Kc3 Kd6 (11.351.269) 4018
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41 0:03 +0.64 53...gxf4 54.gxf4 Bc4 55.Bc2 Be2 56.Bxf5 Bf1 57.Bg4 Bd3 58.Bd1 Bf1 59.Bb3 Bc4 60.Bc2 Be2 61.Bg6 Bf1 62.a4 b5 63.axb5 Bxb5 64.Bf7 Kd6 65.Kb7 Bd7 66.Bg6 Be6 (14.120.286) 4006
41 0:03 +0.64 53...Be4 54.Ba2 gxf4 55.gxf4 Bf3 56.Bb1 Be2 57.Bxf5 Bf1 58.Bg4 Bd3 59.Bd1 Bf1 60.Bb3 Bc4 61.Bc2 Be2 62.Bg6 Bf1 63.a4 b5 64.axb5 Bxb5 65.Bf7 Kd6 66.Kb7 Bd7 (14.120.286) 4006
41 0:03 +0.88 53...Bc4 54.Bc2 Bf1 55.Bxf5 Be2 56.Bc2 Bf3 57.Bd3 Bg2 58.Ka6 Bf3 59.Kb5 Bg4 60.Kb4 Kd6 61.Bb5 Kc7 62.Kc3 Kd6 63.Kd2 Ke6 64.Ba6 Bf3 65.Bd3 Bg4 66.Kc3 Kd6 (14.120.286) 4006
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42 0:03 +0.64 53...gxf4 54.gxf4 Bc4 55.Bc2 Be2 56.Bxf5 Bf1 57.Bg4 Bd3 58.Bd1 Bf1 59.Bb3 Bc4 60.Bc2 Be2 61.Bg6 Bf1 62.a4 b5 63.axb5 Bxb5 64.Bf7 Kd6 65.Kb7 Bd7 66.Bg6 Be6 (15.951.010) 3991
42 0:03 +0.64 53...Be4 54.Ba2 gxf4 55.gxf4 Bf3 56.Bb1 Be2 57.Bxf5 Bf1 58.Bg4 Bd3 59.Bd1 Bf1 60.Bb3 Bc4 61.Bc2 Be2 62.Bg6 Bf1 63.a4 b5 64.axb5 Bxb5 65.Bf7 Kd6 66.Kb7 Bd7 (15.951.010) 3991
42 0:03 +0.88 53...Bc4 54.Bc2 Bf1 55.Bxf5 Be2 56.Bc2 Bf3 57.Bd3 Bg2 58.Ka6 Bf3 59.Kb5 Bg4 60.Kb4 Kd6 61.Bb5 Kc7 62.Kc3 Kd6 63.Kd2 Ke6 64.Bd3 Bf3 65.Kc3 Kd6 66.Ba6 Ke6 (15.951.010) 3991
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43 0:04 +0.64 53...gxf4 54.gxf4 Bc4 55.Bc2 Be2 56.Bxf5 Bf1 57.Bg4 Bd3 58.Bd1 Bf1 59.Bb3 Bc4 60.Bc2 Be2 61.Bg6 Bf1 62.a4 b5 63.axb5 Bxb5 64.Bf7 Kd6 65.Kb7 Bd7 66.Bg6 Be6 (18.370.972) 3993
43 0:04 +0.64 53...Be4 54.Ba2 gxf4 55.gxf4 Bf3 56.Bb1 Be2 57.Bxf5 Bf1 58.Bg4 Bd3 59.Bd1 Bf1 60.Bb3 Bc4 61.Bc2 Be2 62.Bg6 Bf1 63.a4 b5 64.axb5 Bxb5 65.Bf7 Kd6 66.Kb7 Bd7 (18.370.972) 3993
43 0:04 +0.88 53...Bc4 54.Bc2 Bf1 55.Bxf5 Be2 56.Bc2 Bf3 57.Bd3 Bg2 58.Ka6 Bf3 59.Kb5 Bg4 60.Kb4 Kd6 61.Bb5 Kc7 62.Kc3 Kd6 63.Kd2 Ke6 64.Bd3 Bh5 65.Kc3 Bg4 66.Ba6 Bd1 (18.370.972) 3993
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44 0:05 +0.64 53...gxf4 54.gxf4 Bc4 55.Bc2 Be2 56.Bxf5 Bf1 57.Bg4 Bd3 58.Bd1 Bf1 59.Bb3 Bc4 60.Bc2 Be2 61.Bg6 Bf1 62.a4 b5 63.axb5 Bxb5 64.Bf7 Kd6 65.Kb7 Bd7 66.Bg6 Be6 (23.140.726) 3983
44 0:05 +0.64 53...Be4 54.Ba2 gxf4 55.gxf4 Bf3 56.Bb1 Be2 57.Bxf5 Bf1 58.Bg4 Bd3 59.Bd1 Bf1 60.Bb3 Bc4 61.Bc2 Be2 62.Bg6 Bf1 63.a4 b5 64.axb5 Bxb5 65.Bf7 Kd6 66.Kb7 Bd7 (23.140.726) 3983
44 0:05 +0.88 53...Bc4 54.Bc2 Bf1 55.Bxf5 Be2 56.Bc2 Bf3 57.Bd3 Bg2 58.Ka6 Bf3 59.Kb5 Bg4 60.Kb4 Kd6 61.Bb5 Kc7 62.Kc3 Kd6 63.Kd2 Ke6 64.Bd3 Bh5 65.Kc3 Bg4 66.Ba6 Bd1 (23.140.726) 3983
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45 0:09 +0.64 53...gxf4 54.gxf4 Bc4 55.Bc2 Be2 56.Bxf5 Bf1 57.Bg4 Bd3 58.Bd1 Bf1 59.Bb3 Bc4 60.Bc2 Be2 61.Bg6 Bf1 62.a4 b5 63.axb5 Bxb5 64.Bf7 Kd6 65.Kb7 Bd7 66.Bg6 Be6 (36.437.412) 3709
45 0:09 +0.64 53...Be4 54.Ba2 gxf4 55.gxf4 Bf3 56.Bb1 Be2 57.Bxf5 Bf1 58.Bg4 Bd3 59.Bd1 Bf1 60.Bb3 Bc4 61.Bc2 Be2 62.Bg6 Bf1 63.a4 b5 64.axb5 Bxb5 65.Bf7 Kd6 66.Kb7 Bd7 (36.437.412) 3709
45 0:09 +0.94 53...Bc4 54.Bc2 Bf1 55.Bxf5 Be2 56.Bc2 Bf3 57.Bd3 Bg2 58.Ka6 Bf3 59.Kb5 Bh5 60.Bf5 Bf3 61.Kb4 Kc6 62.Kc3 Kd6 63.Kd2 Kc6 64.Bd3 Bg4 65.Bf1 Bf5 66.Be2 Be4 (36.437.412) 3709
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46 0:12 +0.64 53...gxf4 54.gxf4 Bc4 55.Bc2 Be2 56.Bxf5 Bf1 57.Bg4 Bd3 58.Bd1 Bf1 59.Bb3 Bc4 60.Bc2 Be2 61.Bg6 Bf1 62.a4 b5 63.axb5 Bxb5 64.Bf7 Kd6 65.Kb7 Bd7 66.Bg6 Be6 (45.652.311) 3758
46 0:12 +0.64 53...Be4 54.Ba2 gxf4 55.gxf4 Bf3 56.Bb1 Be2 57.Bxf5 Bf1 58.Bg4 Bd3 59.Bd1 Bf1 60.Bb3 Bc4 61.Bc2 Be2 62.Bg6 Bf1 63.a4 b5 64.axb5 Bxb5 65.Bf7 Kd6 66.Kb7 Bd7 (45.652.311) 3758
46 0:12 +0.94 53...Bc4 54.Bc2 Bf1 55.Bxf5 Be2 56.Bc2 Bf3 57.Bd3 Bg2 58.Ka6 Bf3 59.Kb5 Bh5 60.Bf5 Bf3 61.Kb4 Kc6 62.Kc3 Kd6 63.Kd2 Kc6 64.Bd3 Bg4 65.Bf1 Bf5 66.Be2 Be4 (45.652.311) 3758
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47 0:14 +0.64 53...gxf4 54.gxf4 Bc4 55.Bc2 Be2 56.Bxf5 Bf1 57.Bg4 Bd3 58.Bd1 Bf1 59.Bb3 Bc4 60.Bc2 Be2 61.Bg6 Bf1 62.a4 Bh3 63.Bf7 Bg2 64.Be8 Be4 65.Ka6 Bd3+ 66.Bb5 Bf5 (54.436.219) 3774
47 0:14 +0.64 53...Be4 54.Ba2 gxf4 55.gxf4 Bf3 56.Bb1 Be2 57.Bxf5 Bf1 58.Bg4 Bd3 59.Bd1 Bf1 60.Bb3 Bc4 61.Bc2 Be2 62.Bg6 Bf1 63.a4 Bh3 64.Bf7 Bg2 65.Be8 Be4 66.Ka6 Bd3+ (54.436.219) 3774
47 0:14 +0.94 53...Bc4 54.Bc2 Bf1 55.Bxf5 Be2 56.Bc2 Bf3 57.Bd3 Bg2 58.Ka6 Bf3 59.Kb5 Bh5 60.Bf5 Bf3 61.Kb4 Kc6 62.Kc3 Kd6 63.Kd2 Kc6 64.Bd3 Bg4 65.Bf1 Bf5 66.Be2 Be4 (54.436.219) 3774
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48 0:16 +0.64 53...gxf4 54.gxf4 Bc4 55.Bc2 Be2 56.Bxf5 Bf1 57.Bg4 Bd3 58.Bd1 Bf1 59.Bb3 Bc4 60.Bc2 Be2 61.Bg6 Bf1 62.a4 Bh3 63.Bf7 Bg2 64.Be8 Be4 65.Ka6 Bd3+ 66.Bb5 Bf5 (62.766.050) 3801
48 0:16 +0.64 53...Be4 54.Ba2 gxf4 55.gxf4 Bf3 56.Bb1 Be2 57.Bxf5 Bf1 58.Bg4 Bd3 59.Bd1 Bf1 60.Bb3 Bc4 61.Bc2 Be2 62.Bg6 Bf1 63.a4 Bh3 64.Bf7 Bg2 65.Be8 Be4 66.Ka6 Bd3+ (62.766.050) 3801
48 0:16 +0.94 53...Bc4 54.Bc2 Bb5 55.Bxf5 Be2 56.Bc2 Bf3 57.Bd3 Bg2 58.Ka6 Bf3 59.Kb5 Bh5 60.Bf5 Bf3 61.Kb4 Kc6 62.Kc3 Kd6 63.Kd2 Kc6 64.Bd3 Bg4 65.Bf1 Bf5 66.Be2 Be4 (62.766.050) 3801
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49 0:21 +0.64 53...gxf4 54.gxf4 Bc4 55.Bc2 Be2 56.Bxf5 Bf1 57.Bg4 Bd3 58.Bd1 Bf1 59.Bb3 Bc4 60.Bc2 Be2 61.a4 b5 62.axb5 Bxb5 63.Bd1 Bc4 64.Bf3 Ba2 65.Ka6 Kc6 66.Ka5 Bc4 (80.818.403) 3829
49 0:21 +0.64 53...Be4 54.Ba2 gxf4 55.gxf4 Bf3 56.Bb1 Be2 57.Bxf5 Bf1 58.Bg4 Bd3 59.Bd1 Bf1 60.Bb3 Bc4 61.Bc2 Be2 62.a4 b5 63.axb5 Bxb5 64.Bd1 Bc4 65.Bf3 Ba2 66.Ka6 Kc6 (80.818.403) 3829
49 0:21 +0.94 53...Bc4 54.Bc2 Bb5 55.Bxf5 Be2 56.Bc2 Bf3 57.Bd3 Bg2 58.Ka6 Bf3 59.Kb5 Bh5 60.Bf5 Bf3 61.Kb4 Kc6 62.Kc3 Kd6 63.Kd2 Kc6 64.Bd3 Bg4 65.Bf1 Bf5 66.Be2 Be4 (80.818.403) 3829
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50 0:25 +0.64 53...gxf4 54.gxf4 Bc4 55.Bc2 Be2 56.Bxf5 Bf1 57.Bg4 Bd3 58.Bd1 Bf1 59.Bb3 Bc4 60.Bc2 Be2 61.a4 b5 62.axb5 Bxb5 63.Bd1 Bc4 64.Bf3 Ba2 65.Ka6 Kc6 66.Ka5 Bc4 (97.597.482) 3860
50 0:25 +0.64 53...Be4 54.Ba2 gxf4 55.gxf4 Bf3 56.Bb1 Be2 57.Bxf5 Bf1 58.Bg4 Bd3 59.Bd1 Bf1 60.Bb3 Bc4 61.Bc2 Be2 62.a4 b5 63.axb5 Bxb5 64.Bd1 Bc4 65.Bf3 Ba2 66.Ka6 Kc6 (97.597.482) 3860
50 0:25 +0.94 53...Bc4 54.Bc2 Bb5 55.Bxf5 Be2 56.Bc2 Bf3 57.Bd3 Bg2 58.Ka6 Bf3 59.Kb5 Bh5 60.Bf5 Bf3 61.Kb4 Kc6 62.Kc3 Kd6 63.Kd2 Kc6 64.Bd3 Bg4 65.Bf1 Bf5 66.Be2 Be4 (97.597.482) 3860
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51 0:29 +0.64 53...gxf4 54.gxf4 Bc4 55.Bc2 Be2 56.Bxf5 Bf1 57.Bg4 Bd3 58.Bd1 Bf1 59.Bb3 Bc4 60.Bc2 Be2 61.a4 b5 62.axb5 Bxb5 63.Bd1 Bc4 64.Bf3 Ba2 65.Ka6 Kc6 66.Ka5 Bc4 (113.362.855) 3876
51 0:29 +0.64 53...Be4 54.Ba2 gxf4 55.gxf4 Bf3 56.Bb1 Be2 57.Bxf5 Bf1 58.Bg4 Bd3 59.Bd1 Bf1 60.Bb3 Bc4 61.Bc2 Be2 62.a4 b5 63.axb5 Bxb5 64.Bd1 Bc4 65.Bf3 Ba2 66.Ka6 Kc6 (113.362.855) 3876
51 0:29 +0.94 53...Bc4 54.Bc2 Bb5 55.Bxf5 Be2 56.Bc2 Bf3 57.Bd3 Bg2 58.Ka6 Bf3 59.Kb5 Bh5 60.Bf5 Bf3 61.Kb4 Kc6 62.Kc3 Kd6 63.Kd2 Kc6 64.Bd3 Bg4 65.Bf1 Bf5 66.Be2 Be4 (113.362.855) 3876
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52 0:34 +0.64 53...gxf4 54.gxf4 Bc4 55.Bc2 Be2 56.Bxf5 Bf1 57.Bg4 Bd3 58.Bd1 Bf1 59.Bb3 Bc4 60.Bc2 Be2 61.a4 b5 62.axb5 Bxb5 63.Bd1 Bc4 64.Bf3 Ba2 65.Ka6 Kc6 66.Ka5 Bc4 (133.469.645) 3899
52 0:34 +0.64 53...Be4 54.Ba2 gxf4 55.gxf4 Bf3 56.Bb1 Be2 57.Bxf5 Bf1 58.Bg4 Bd3 59.Bd1 Bf1 60.Bb3 Bc4 61.Bc2 Be2 62.a4 b5 63.axb5 Bxb5 64.Bd1 Bc4 65.Bf3 Ba2 66.Ka6 Kc6 (133.469.645) 3899
52 0:34 +0.94 53...Bc4 54.Bc2 Bb5 55.Bxf5 Be2 56.Bc2 Bf3 57.Bd3 Bg2 58.Ka6 Bf3 59.Kb5 Bh5 60.Bf5 Bf3 61.Kb4 Kc6 62.Kc3 Kd6 63.Kd2 Kc6 64.Bd3 Bg4 65.Bf1 Bf5 66.Be2 Be4 (133.469.645) 3899
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53 0:44 +0.64 53...gxf4 54.gxf4 Bc4 55.Bc2 Be2 56.Bxf5 Bf1 57.Bg4 Bd3 58.Bd1 Bf1 59.Bb3 Bc4 60.Bc2 Be2 61.a4 b5 62.axb5 Bxb5 63.Bd1 Bc4 64.Bf3 Ba2 65.Ka6 Kc6 66.Ka5 Bc4 (176.008.258) 3940
53 0:44 +0.64 53...Be4 54.Ba2 gxf4 55.gxf4 Bf3 56.Bb1 Be2 57.Bxf5 Bf1 58.Bg4 Bd3 59.Bd1 Bf1 60.Bb3 Bc4 61.Bc2 Be2 62.a4 b5 63.axb5 Bxb5 64.Bd1 Bc4 65.Bf3 Ba2 66.Ka6 Kc6 (176.008.258) 3940
53 0:44 +0.94 53...Bc4 54.Bc2 Bb5 55.Bxf5 Be2 56.Bc2 Bf3 57.Bd3 Bg2 58.Ka6 Bf3 59.Kb5 Bh5 60.Bf5 Bf3 61.Kb4 Kc6 62.Kc3 Kd6 63.Kd2 Kc6 64.Bd3 Bg4 65.Bf1 Bf5 66.Be2 Be4 (176.008.258) 3940
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54 0:51 +0.64 53...gxf4 54.gxf4 Bc4 55.Bc2 Be2 56.Bxf5 Bf1 57.Bg4 Bd3 58.Bd1 Bf1 59.Bb3 Bc4 60.Bc2 Be2 61.a4 b5 62.axb5 Bxb5 63.Bd1 Bc4 64.Bf3 Bb3 65.Bh5 Bc2 66.Bf7 Be4 (203.371.130) 3947
54 0:51 +0.64 53...Be4 54.Ba2 gxf4 55.gxf4 Bf3 56.Bb1 Be2 57.Bxf5 Bf1 58.Bg4 Bd3 59.Bd1 Bf1 60.Bb3 Bc4 61.Bc2 Be2 62.a4 b5 63.axb5 Bxb5 64.Bd1 Bc4 65.Bf3 Bb3 66.Bh5 Bc2 (203.371.130) 3947
54 0:51 +0.94 53...Bc4 54.Bc2 Bb5 55.Bxf5 Be2 56.Bc2 Bf3 57.Bd3 Bg2 58.Ka6 Bf3 59.Kb5 Bh5 60.Bf5 Bf3 61.Kb4 Kc6 62.Kc3 Kd6 63.Kd2 Kc6 64.Bd3 Bg4 65.Bf1 Bf5 66.Be2 Be4 (203.371.130) 3947
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55 1:00 +0.64 53...gxf4 54.gxf4 Bc4 55.Bc2 Be2 56.Bxf5 Bf1 57.Bg4 Bd3 58.Bd1 Bf1 59.Bb3 Bc4 60.Bc2 Be2 61.a4 b5 62.axb5 Bxb5 63.Bd1 Bc4 64.Bf3 Bb3 65.Bh5 Bc2 66.Bf7 Be4 (239.566.668) 3968
55 1:00 +0.64 53...Be4 54.Ba2 gxf4 55.gxf4 Bf3 56.Bb1 Be2 57.Bxf5 Bf1 58.Bg4 Bd3 59.Bd1 Bf1 60.Bb3 Bc4 61.Bc2 Be2 62.a4 b5 63.axb5 Bxb5 64.Bd1 Bc4 65.Bf3 Bb3 66.Bh5 Bc2 (239.566.668) 3968
55 1:00 +0.94 53...Bc4 54.Bc2 Bb5 55.Bxf5 Be2 56.Bc2 Bf3 57.Bd3 Bg2 58.Ka6 Bf3 59.Kb5 Bh5 60.Bf5 Bf3 61.Kb4 Kc6 62.Kc3 Kd6 63.Kd2 Kc6 64.Bd3 Bg4 65.Bf1 Bf5 66.Be2 Be4 (239.566.668) 3968
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56 1:05 +0.64 53...gxf4 54.gxf4 Bc4 55.Bc2 Be2 56.Bxf5 Bf1 57.Bg4 Bd3 58.Bd1 Bf1 59.Bb3 Bc4 60.Bc2 Be2 61.a4 b5 62.axb5 Bxb5 63.Bd1 Bc4 64.Bf3 Bb3 65.Bh5 Bc2 66.Bf7 Be4 (260.363.851) 3970
56 1:05 +0.64 53...Be4 54.Ba2 gxf4 55.gxf4 Bf3 56.Bb1 Be2 57.Bxf5 Bf1 58.Bg4 Bd3 59.Bd1 Bf1 60.Bb3 Bc4 61.Bc2 Be2 62.a4 b5 63.axb5 Bxb5 64.Bd1 Bc4 65.Bf3 Bb3 66.Bh5 Bc2 (260.363.851) 3970
56 1:05 +0.94 53...Bc4 54.Bc2 Bb5 55.Bxf5 Be2 56.Bc2 Bf3 57.Bd3 Bg2 58.Ka6 Bf3 59.Kb5 Bh5 60.Bf5 Bf3 61.Kb4 Kc6 62.Kc3 Kd6 63.Kd2 Kc6 64.Bd3 Bg4 65.Bf1 Bf5 66.Be2 Be4 (260.363.851) 3970
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57 1:18 +0.64 53...gxf4 54.gxf4 Bc4 55.Bc2 Be2 56.Bxf5 Bf1 57.Bg4 Bd3 58.Bd1 Bf1 59.Bb3 Bc4 60.Bc2 Be2 61.a4 b5 62.axb5 Bxb5 63.Bd1 Bc4 64.Bf3 Bb3 65.Bh5 Bc2 66.Bf7 Be4 (311.282.215) 3984
57 1:18 +0.64 53...Be4 54.Ba2 gxf4 55.gxf4 Bf3 56.Bb1 Be2 57.Bxf5 Bf1 58.Bg4 Bd3 59.Bd1 Bf1 60.Bb3 Bc4 61.Bc2 Be2 62.a4 b5 63.axb5 Bxb5 64.Bd1 Bc4 65.Bf3 Bb3 66.Bh5 Bc2 (311.282.215) 3984
57 1:18 +0.94 53...Bc4 54.Bc2 Bb5 55.Bxf5 Be2 56.Bc2 Bf3 57.Bd3 Bg2 58.Ka6 Bf3 59.Kb5 Bh5 60.Bf5 Bf3 61.Kb4 Kc6 62.Kc3 Kd6 63.Kd2 Kc6 64.Bd3 Bg4 65.Bf1 Bf5 66.Be2 Be4 (311.282.215) 3984
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58 1:27 +0.64 53...gxf4 54.gxf4 Bc4 55.Bc2 Be2 56.Bxf5 Bf1 57.Bg4 Bd3 58.Bd1 Bf1 59.Bb3 Bc4 60.Bc2 Be2 61.a4 b5 62.axb5 Bxb5 63.Bd1 Bd3 64.Bf3 Kc6 65.Kb8 Bf5 66.Bg2 Bg4 (351.339.507) 3997
58 1:27 +0.64 53...Be4 54.Ba2 gxf4 55.gxf4 Bf3 56.Bb1 Be2 57.Bxf5 Bf1 58.Bg4 Bd3 59.Bd1 Bf1 60.Bb3 Bc4 61.Bc2 Be2 62.a4 b5 63.axb5 Bxb5 64.Bd1 Bd3 65.Bf3 Kc6 66.Kb8 Bf5 (351.339.507) 3997
58 1:27 +0.94 53...Bc4 54.Bc2 Bb5 55.Bxf5 Be2 56.Bc2 Bf3 57.Bd3 Bg2 58.Ka6 Bf3 59.Kb5 Bh5 60.Bf5 Bf3 61.Kb4 Kc6 62.Kc3 Kd6 63.Kd2 Kc6 64.Bd3 Bg4 65.Bf1 Bf5 66.Be2 Be4 (351.339.507) 3997
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59 1:46 +0.64 53...gxf4 54.gxf4 Bc4 55.Bc2 Be2 56.Bxf5 Bf1 57.Bg4 Bd3 58.Bd1 Bf1 59.Bb3 Bc4 60.Bc2 Be2 61.a4 b5 62.axb5 Bxb5 63.Bd1 Bd3 64.Bf3 Kc6 65.Kb8 Bf5 66.Bg2 Bg4 (427.135.553) 4008
59 1:46 +0.64 53...Be4 54.Ba2 gxf4 55.gxf4 Bf3 56.Bb1 Be2 57.Bxf5 Bf1 58.Bg4 Bd3 59.Bd1 Bf1 60.Bb3 Bc4 61.Bc2 Be2 62.a4 b5 63.axb5 Bxb5 64.Bd1 Bd3 65.Bf3 Kc6 66.Kb8 Bf5 (427.135.553) 4008
59 1:46 +0.94 53...Bc4 54.Bc2 Bb5 55.Bxf5 Be2 56.Bc2 Bf3 57.Bd3 Bg2 58.Ka6 Bf3 59.Kb5 Bh5 60.Bf5 Bf3 61.Kb4 Kc6 62.Kc3 Kd6 63.Kd2 Kc6 64.Bd3 Bg4 65.Bf1 Bf5 66.Be2 Be4 (427.135.553) 4008
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60 1:59 +0.64 53...gxf4 54.gxf4 Bc4 55.Bc2 Be2 56.Bxf5 Bf1 57.Bg4 Bd3 58.Bd1 Bf1 59.Bb3 Bc4 60.Bc2 Be2 61.a4 b5 62.axb5 Bxb5 63.Bd1 Bd3 64.Bf3 Kc6 65.Kb8 Bf5 66.Bg2 Bg4 (480.506.262) 4026
60 1:59 +0.64 53...Be4 54.Ba2 gxf4 55.gxf4 Bf3 56.Bb1 Be2 57.Bxf5 Bf1 58.Bg4 Bd3 59.Bd1 Bf1 60.Bb3 Bc4 61.Bc2 Be2 62.a4 b5 63.axb5 Bxb5 64.Bd1 Bd3 65.Bf3 Kc6 66.Kb8 Bf5 (480.506.262) 4026
60 1:59 +0.94 53...Bc4 54.Bc2 Bb5 55.Bxf5 Be2 56.Bc2 Bf3 57.Bd3 Bg2 58.Ka6 Bf3 59.Kb5 Bh5 60.Bf5 Bf3 61.Kb4 Kc6 62.Kc3 Kd6 63.Kd2 Kc6 64.Bd3 Bg4 65.Bf1 Bf5 66.Be2 Be4 (480.506.262) 4026
So, it looks like Be4 and gxf4 just transpose and there's no progress to be seen.
Why do I only analyze it for 2 minutes? Because I analyse by depth, not by time, lest I'd waste too much time in obvious moves and recaptures. Why don't I analyze higher than Depth 60? Because this was just one of many lines I analyzed, I figured Depth 60 was good enough and fast enough to let me analyze as much as possible. Oops.
Now I play a game again to simulate what would happen, but instead of depth 28 I use Depth 60, the reply by white is...
35/46 0:01 +0.60 54.gxf4 Be4 55.Bd1 Bd3 56.Bh5 Bf1 57.Bf7 Bg2 58.Be8 Be4 59.Bb5 Bc2 60.Ba6 Be4 61.Be2 Bc2 62.Ka6 Kc6 63.Bf3 Bb3 64.Bh5 Bc2 65.Be8+ Kc7 66.Kb5 Bd3+ 67.Kb4 (1.809.928) 1172
36/44 0:01 +0.54 54.gxf4 Be4 55.Bd1 Bd3 56.Bh5 Bf1 57.Be8 Bd3 58.Bg6 Bb1 59.Bh5 Bd3 60.Be8 Be4 61.Bf7 Bf3 62.Bg6 Bg4 63.Ka8 Bh3 64.Bf7 Bg2 65.Bh5 Be4 66.Be2 Bc2 67.Ba6 (1.998.646) 1178
37/46 0:02 +0.54 54.gxf4 Be4 55.Bd1 Bd3 56.Bh5 Bf1 57.Be8 Bd3 58.Bg6 Bb1 59.Bh5 Bd3 60.Be8 Be4 61.Bf7 Bf3 62.Bg6 Bg4 63.Ka8 Bh3 64.Bf7 Bg2 65.Be6 Be4 66.Ka7 Kd6 67.Bc8 (2.575.251) 1180
38/47 0:03 +0.66 54.gxf4 Be4 55.Bd1 Bb1 56.Bf3 Ba2 57.Be2 Bb1 58.Bd1 Be4 59.Bb3 Bf3 60.Bc2 Be2 61.Bxf5 Bf1 62.Be6 Bg2 63.Bf7 Bf3 64.Bg6 Be2 65.Be8 Bf1 66.Bf7 Bg2 67.Bg6 (4.010.595) 1196
39/47 0:04 +0.60 54.gxf4 Be4 55.Bd1 Bb1 56.Bf3 Ba2 57.Be2 Bb1 58.Bd1 Be4 59.Bb3 Bf3 60.Bc2 Be2 61.Bxf5 Bf1 62.Be6 Bg2 63.Bg4 Bf1 64.Bf5 Be2 65.Be6 Bf3 66.Bh3 Be2 67.Bg2 (5.048.908) 1191
40/50 0:04 +0.60 54.gxf4 Be4 55.Bd1 Bb1 56.Bf3 Ba2 57.Be2 Bb1 58.Bd1 Be4 59.Bb3 Bf3 60.Bc2 Be2 61.Bxf5 Bf1 62.Be6 Bg2 63.Bg4 Bf1 64.Bf5 Be2 65.Be6 Bf3 66.Bh3 Be2 67.Bg2 (5.339.985) 1193
41/51 0:04 +0.60 54.gxf4 Be4 55.Bd1 Bb1 56.Bf3 Ba2 57.Be2 Bb1 58.Bd1 Be4 59.Bb3 Bf3 60.Bc2 Be2 61.Bxf5 Bf1 62.Be6 Bg2 63.Bg4 Bf1 64.Bf5 Be2 65.Be6 Bf3 66.Bh3 Be2 67.Bg2 (5.506.471) 1191
42/57 0:05 +0.60 54.gxf4 Be4 55.Bd1 Bb1 56.Bf3 Ba2 57.Be2 Bb1 58.Bd1 Be4 59.Bb3 Bf3 60.Bc2 Be2 61.Bxf5 Bf1 62.Be6 Bg2 63.Bg4 Bf1 64.Bf5 Be2 65.Be6 Bf3 66.Bh3 Be2 67.Bg2 (6.540.427) 1199
43/55 0:05 +0.60 54.gxf4 Be4 55.Bd1 Bb1 56.Bf3 Ba2 57.Be2 Bb1 58.Bd1 Be4 59.Bb3 Bf3 60.Bc2 Be2 61.Bxf5 Bf1 62.Be6 Bg2 63.Bg4 Bf1 64.Bf5 Be2 65.Be6 Bf3 66.Bh3 Be2 67.Bg2 (6.929.096) 1201
44/59 0:07 +0.67 54.gxf4 Be4 55.Ba2 Bf3 56.Bb1 Be2 57.Bxf5 Bf1 58.Be6 Bg2 59.Bg4 Bf1 60.Bf5 Be2 61.Be6 Bf3 62.Bh3 Be2 63.Bg2 Bc4 64.Bf3 Bb3 65.Bh5 Bc2 66.Be2 Bb3 67.Bb5 (9.049.115) 1213
45/59 0:08 +0.62 54.gxf4 Be4 55.Ba2 Bf3 56.Bb1 Be2 57.Bxf5 Bf1 58.Be6 Bg2 59.Bg4 Bf1 60.Bf5 Be2 61.Be6 Bf3 62.Bh3 Be2 63.Ka8 Bd3 64.Bg2 Bc4 65.Ka7 Bb3 66.Bh3 Bc2 67.Bf1 (10.515.288) 1214
46/59 0:09 +0.65 54.gxf4 Be4 55.Ba2 Bf3 56.Bb1 Be2 57.Bxf5 Bf1 58.Be6 Bg2 59.Bg4 Bf1 60.Bf5 Be2 61.Bg6 Bf1 62.Bf7 Bg2 63.Be6 Be4 64.a4 Bg2 65.Bg8 Be4 66.Bf7 Bf3 67.Be8 (11.863.128) 1213
47/62 0:11 +0.67 54.gxf4 Be4 55.Ba2 Bf3 56.Bb1 Be2 57.Bxf5 Bf1 58.Bg6 Be2 59.Be8 Bd3 60.a4 Be4 61.Ka6 Bd3+ 62.Bb5 Bc2 63.a5 bxa5 64.Kxa5 Kd6 65.Kb4 Bf5 66.Kc3 Bb1 67.Ba6 (14.302.200) 1217
48/53 0:13 +0.67 54.gxf4 Be4 55.Ba2 Bf3 56.Bb1 Be2 57.Bxf5 Bf1 58.Bg6 Be2 59.Be8 Bd3 60.a4 Be4 61.Ka6 Bd3+ 62.Bb5 Bc2 63.a5 bxa5 64.Kxa5 Kd6 65.Kb4 Bf5 66.Kc3 Bb1 67.Ba6 (16.357.805) 1216
49/56 0:15 +0.67 54.gxf4 Be4 55.Ba2 Bf3 56.Bb1 Be2 57.Bxf5 Bf1 58.Bg6 Be2 59.Be8 Bd3 60.a4 Be4 61.Ka6 Bd3+ 62.Bb5 Bc2 63.a5 bxa5 64.Kxa5 Kd6 65.Kb4 Bf5 66.Kc3 Bb1 67.Ba6 (18.454.225) 1214
50/59 0:16 +0.67 54.gxf4 Be4 55.Ba2 Bf3 56.Bb1 Be2 57.Bxf5 Bf1 58.Bg6 Be2 59.Be8 Bd3 60.a4 Be4 61.Ka6 Bd3+ 62.Bb5 Bc2 63.a5 bxa5 64.Kxa5 Kd6 65.Kb4 Bf5 66.Kc3 Bb1 67.Ba6 (19.825.556) 1215
51/58 0:18 +0.67 54.gxf4 Be4 55.Ba2 Bf3 56.Bb1 Be2 57.Bxf5 Bf1 58.Bg6 Be2 59.Be8 Bd3 60.a4 Be4 61.Ka6 Bd3+ 62.Bb5 Bc2 63.a5 bxa5 64.Kxa5 Kd6 65.Kb4 Bf5 66.Kc3 Bb1 67.Ba6 (22.711.060) 1218
52/57 0:21 +0.67 54.gxf4 Be4 55.Ba2 Bf3 56.Bb1 Be2 57.Bxf5 Bf1 58.Bg6 Be2 59.Be8 Bd3 60.a4 Be4 61.Ka6 Bd3+ 62.Bb5 Bc2 63.a5 bxa5 64.Kxa5 Kd6 65.Kb4 Bf5 66.Kc3 Bb1 67.Ba6 (25.812.214) 1220
53/59 0:23 +0.67 54.gxf4 Be4 55.Ba2 Bf3 56.Bb1 Be2 57.Bxf5 Bf1 58.Bg6 Be2 59.Be8 Bd3 60.a4 Be4 61.Ka6 Bd3+ 62.Bb5 Bc2 63.a5 bxa5 64.Kxa5 Kd6 65.Kb4 Bf5 66.Kc3 Bb1 67.Ba6 (28.330.347) 1220
54/61 0:27 +0.67 54.gxf4 Be4 55.Ba2 Bf3 56.Bb1 Be2 57.Bxf5 Bf1 58.Bg6 Be2 59.Be8 Bd3 60.a4 Be4 61.Ka6 Bd3+ 62.Bb5 Bc2 63.a5 bxa5 64.Kxa5 Bf5 65.Kb4 Kd6 66.Kc3 Bb1 67.Ba6 (33.384.814) 1221
55/63 0:29 +0.67 54.gxf4 Be4 55.Ba2 Bf3 56.Bb1 Be2 57.Bxf5 Bf1 58.Bg6 Be2 59.Be8 Bd3 60.a4 Be4 61.Ka6 Bd3+ 62.Bb5 Bc2 63.a5 bxa5 64.Kxa5 Bf5 65.Kb4 Kd6 66.Kc3 Bb1 67.Ba6 (35.715.256) 1223
56/62 0:31 +0.67 54.gxf4 Be4 55.Ba2 Bf3 56.Bb1 Be2 57.Bxf5 Bf1 58.Bg6 Be2 59.Be8 Bd3 60.a4 Be4 61.Ka6 Bd3+ 62.Bb5 Bc2 63.a5 bxa5 64.Kxa5 Bf5 65.Kb4 Kd6 66.Kc3 Bb1 67.Ba6 (39.004.717) 1225
57/63 0:35 +0.67 54.gxf4 Be4 55.Ba2 Bf3 56.Bb1 Be2 57.Bxf5 Bf1 58.Bg6 Be2 59.Be8 Bd3 60.a4 Be4 61.Ka6 Bd3+ 62.Bb5 Bc2 63.a5 bxa5 64.Kxa5 Bf5 65.Kb4 Kd6 66.Kc3 Bb1 67.Ba6 (42.997.237) 1225
58/68 0:39 +0.67 54.gxf4 Be4 55.Ba2 Bf3 56.Bb1 Be2 57.Bxf5 Bf1 58.Bg6 Be2 59.Be8 Bd3 60.a4 Be4 61.Ka6 Bd3+ 62.Bb5 Bc2 63.a5 bxa5 64.Kxa5 Bf5 65.Kb4 Kd6 66.Kc3 Bb1 67.Ba6 (49.081.164) 1227
59/62 0:42 +0.67 54.gxf4 Be4 55.Ba2 Bf3 56.Bb1 Be2 57.Bxf5 Bf1 58.Bg6 Be2 59.Be8 Bd3 60.a4 Be4 61.Ka6 Bd3+ 62.Bb5 Bc2 63.a5 bxa5 64.Kxa5 Bf5 65.Kb4 Kd6 66.Kc3 Bb1 67.Ba6 (51.752.781) 1227
60/64 0:50 +0.67 54.gxf4 Be4 55.Ba2 Bf3 56.Bb1 Be2 57.Bxf5 Bf1 58.Bg6 Be2 59.Be8 Bd3 60.a4 Be4 61.Ka6 Bd3+ 62.Bb5 Bc2 63.a5 bxa5 64.Kxa5 Bf5 65.Kb4 Kd6 66.Kc3 Bb1 67.Ba6 (61.709.833) 1225
And the rest of the moves lead to a drawn game again.
I assume the opponent has nothing and he's just prolonging the game (that's what I was thinking since move 40, as I hadn't seen a single white win in analysis, so this position didn't seem special at all), so I play 53...gxf4?? and lose the game.
Had I used MultiPV to look for alternative moves for the opponent, I'd have seen the key move that had White winning. For some reason I thought that if I could draw Depth 60 McCain X I could draw against anything.
Uri Blass wrote:Note that with multi-pv of 2 moves stockfish is clearly faster and it may be interesting to have a match between stockfish and itself with fixed time per move when one engine use multi-pv with 2 options and the second use only one option and I wonder if there is some interface that allow it.
Sure, the Shredder GUI allows for this, just add MultiPV=2 to engine options to a personality file and have them play. For more versatility you'd want to try the Lucas Chess GUI (where you could play different engines at different Depths and MultiPVs, while Shredder only allows same depth.)
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