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| Nov-14-18 | | centralfiles: As for engine favorite 20.Bd5...
click for larger viewThis is the line i was talking about earlier when I said the computer can't see deep enough. I do not mean that Kwid's sees more plies or some other ridiculous notion like that. Rather that this position is one where a human with good positional understanding can see much deeper than even a good engine that's given a long time to evaluate. Let's have a look at the actual drawing line (supplied eons ago by <Kwid> see my post above) and how the computer evaluates it. We'll also try to figure out how long it might take an engine to find it. 20...Kd8!
already we have a move the engines would not look at as first choice. In the engine's view 20...Rxf4 or 20...a6 seem to be better(these are actually both inferior alternatives). 21.Ne4 
click for larger viewAnd here engine evals are already beginning to approach dangerous +1.5 levels recommending 21...Rg6 21...Rxf4 Huh? this isn't even one of the engines top 3-4 choices.
At this point the engines initial evaluations are already well over +2.00 If we didn't know better we would never bother looking further surely white must be winning here... 22.Nexd6
click for larger view
22...Bg4!
Now after a few moments the engine begins to realize it's not quite as bad as it thought though it's still evaluating at +1.5ish with 2-3 moves that seem good 23.Qd3
23.Nxb7+
And 23.Qc1 though this last options quickly dissipates after a few moments to an eval of 0.00 The other options seem last a little longer:
23.Qd3 Ne5 24.Qxh7 a6(24...Kd7 25.hxg4 Ng6 is drawn as well though kwids ...a6 line is nice and takes longer for engines to find) 25.Nxb7+ Kd7 26.Nd4 Raf8 27.Rxe3 Rf1+ 28.Rxf1 Rxf1+ 29.Kh2 Qf8/Kc8 With an eval of 0.00 after only a moment or two.
Any deviation<for white> along the way is simply a quicker route to an eval of 0.00. 23.Nxb7+ Kc8 24.N7d6+(24.N5d6+ Kc7 =) Kd7 25.Qc2
click for larger view
And now 25...a6 is probably sufficient to draw
But deeper is Kwid's 25...Qg5! 25.Be4 Rd8 = |
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| Nov-14-18 | | centralfiles: So in conclusion what does the engine say about the 20.Bd5 line? DEAD EQUAL!!
At the end of the sliding there is not a single alternative remaining anywhere along the line where the engine (given a few moments) thinks white has any real advantage at all. Everything peters out to 0.00 or some eval close to that. But how long would it take for the engine to see this at move 20.????
Hard to answer definitively of course, but seeing as so many of the moves were far down the engines list of its top choices and were initially evaluated very poorly by the engine, it would take several days at the very least and probably much longer for an engine running at move 20 to see this far. Yet this is something anyone running stockfish 9 with a half decent cpu <I'm using an i5-6200u which is unimpressive ("u" laptop processors do not perform anything like their desktop counterparts)> can see for themselves in about 20 minutes. The power of hindsight <kwid's provided lines> and sliding is far greater than days or even weeks of computer time. |
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| Nov-14-18 | | centralfiles: BUT WAIT:
How do we know that somewhere deeper along some line the engine won't find some new idea for white that makes the evaluation suddenly jump from equal to +1.5 with a winning advantage? Didn't we just see the engines doing just this for black when evals of +2.00 suddenly fell to 0.00?
Surely the only way to check is to allow the engine time to search exhaustively through every possibility it can?This is actually a reasonable objection. Indeed we can't possibly know 100% that there is no hidden deep winning ideas for white which the engine is missing. Yet we have no reason to assume such a possibility is true merely because it theoretically can be.
If we are looking at positions where the engines are generally appreciating the value of white's advantage there's no reason to assume that any given position where the engine is evaluating 0.00 after a few moments might actually be winning for white.
This would be a different story entirely if white's positional advantages had been of the type where the engines have a hard time appreciating their latent value
I.e. this would be a terrible way to evaluate white's chances in a deep sacrificial line.
Judging when the engines are underappreciating the latent strength of one side's position<in many complex position this could be both sides simultaneously> and understanding which moves are most likely to bring those strengths to bear is crucial for effective "sliding"
which IMO <which I'm confident is shared by many others> is by far the most effective way to analyze with an engine.
This kind of sliding<made very easy by kwid"s provided analysis> is what led me many months ago to quickly conclude 19...Rf6 draws. I was able to find the most problematic line 20.Rb1 Kd8 21.Qd5 Bd7 22.Red1!? right away using these methods see Team White vs Team Black, 2017 (kibitz #3210) I will try to post the full analysis of 19...Rf6 with engine evals and named variations for reference purposes shortly. |
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| Nov-14-18 | | centralfiles: As far as engine tournaments go:
In this kind of situation where we are primarily trying to figure out if a certain move draws with best play it's hard to see any value to them at all.
The lines seem to be full of "critical junctures" where finding the correct move is crucial. Why would we care at all about the result of engine games where the black engine failed to find 20.Bd5 20...Kd8! for example? Having many more plies after that would not be able to compensate in any way here.They seem most useful in complex unclear positions with many good ideas for both sides where we are trying to evaluate who has the better practical chances, not if one side is objectively "won". Judging from your last post you probably mostly agree here. |
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| Nov-14-18 | | centralfiles: A little OFF TOPIC but once were discussing engines/sliding. I must say I'm a bit surprised at some of the effects of stockfish 9s aggressive pruning. Take this uber famous game: Hamppe vs Meitner, 1872
After 11.a5+ older relatively weak engines such as fritz10 can quickly see the draw. Stockfish 8 does not fare too badly either here.
But Stockfish 9 is totally oblivious going all the way to 14...b6+ until it reluctantly finds the draw after a half a minute. And all this because it is agressively pruning out 15...Nxc6 looking only at 15...Ba6+ Ka4 Nxc6. Pretty nuts. No? |
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| Nov-14-18 | | centralfiles: <Kwid> I wrote my Bd5 analysis post before i read your most recent post.
The lines are the same for the most part.
After all i used your analysis. Though i see you switched to 25...a6 which is fine too but why not your old 25...Qg5? I liked it better ;) |
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| Nov-15-18 | | kwid: <centralfiles: <Kwid> why not your old 25...Qg5?> Good question since the position reached with Qg5 seems to culminate the intend of the Traxler Counter Gambit from the Romantic Area with creations from players like Murphy etc. But we leave now in the "Bean Counter" times grinding out variations by the numbers with no room for art anymore. Oh well here we are:
click for larger view25. ... Qg5 26. Bc4 Ne5 27. Rad1 Bxd1 28. Qxd1 Ke7 29. Qd5 Rd8 30. Qe6+ Kf8 31. Qg8+ 1/2-1/2 
click for larger view |
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Nov-16-18
 | | AylerKupp: <<kwid> Well, if you look at my last Rb1 line your engines may agree to a draw and thus game over. As to Bd5 I still have a game analysis which also shows no win for white in sight and thus if your engines agree we should stop searching for a win if black plays 19...Rf6.> If after going down both lines and having the engines agree that both lines lead to a draw I will readily agree that <these 2 lines> lead to a draw. But that's a far cry from agreeing that <all> lines following 19...Rf6 will lead to a draw. As I've said before, I don't think that this approach of cherry-picking specific lines will demonstrate conclusively that <all> lines following 19...Rf6 will lead to a draw. |
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Nov-16-18
| | AylerKupp: <<centralfiles> As far as "confirming" 19...Rf6 draws. I'm afraid <AK> and <kwid> clearly both mean well but somehow you guys don't seem to be on the same page.> Yes, you're right. I'm doing these analyses because <kwid> asked me to. I told him a long time ago that I did not believe that a long analysis of a single line, or even a few lines, would conclusively demonstrate that after 19...Rf6 the position is a draw for <all> lines. There are simply too many reasonable alternative lines for either a human or computer to investigate before such a conclusion can be reached. And so far <kwid> hasn't given me any reason that would cause me to change my mind. And, frankly, that same comment applies to your main line given in Team White vs Team Black, 2017 (kibitz #3684). One line and one alternative line is not a valid indication that <all> lines following 19...Rf6 will lead to, at worst, a draw for Black. Going back to your following post Team White vs Team Black, 2017 (kibitz #3685) and your "win friendly rules"; If engine consistently 1.3 or higher in final position we'll consider it probable win. Your assessment thresholds are, as you indicated, too optimistic. FWIW, these are the ones I use (from White's perspective): Your assessment thresholds are, as you indicated, too optimistic. FWIW, these are the ones I use (from White's perspective): [0.00] to [+0.49] = <Equal> [+0.50] to [+0.99] = <White is slightly better> [+1.00] to [+1.99] = <White is significantly better> [+2.00] & Up = <White has a winning advantage> The first 3 is how most chess GUIs assess the position and corresponds to my theory (and others', most recently Svidler in its <chess24.com> commentary of Carlsen vs Caruana, 2018) that a human analyst's "resolution" is the equivalent of [ ±0.5] centipawns. Some GUIs assess any evaluation of [+1.50] & up to indicate that White has a winning advantage but I prefer to be more conservative and insisting on an evaluation of [+2.00] and up to assess the position as White having a winning advantage. But to each their own. |
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Nov-16-18
| | AylerKupp: <<centralfiles? As for engine favorite 20.Bd5 ... This is the line i was talking about earlier when I said the computer can't see deep enough.> True, at least in any reasonable amount of time; for example, in the remainder of my lifetime. In order for the computer to see deep enough you have to perform some forward sliding to try to eliminate or at least defer the impact of the horizon effect. And this I haven't attempted to do since all I offered to do is to run some 3-engine analyses on <kwid>'s main line to see how the moves in his analysis compare with the moves that the 3-engines considered best. |
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Nov-16-18
| | AylerKupp: <<centralfiles> 20...Kd8! already we have a move the engines would not look at as first choice.> You list a few moves with some subjective commentary but you never indicate what engine(s) you were using and what was the search ply at which the engine reached the evaluations you listed, although I suspect you were using some version of Stockfish. Was this just an oversight? The engine use and the search depth reach are important in determining how much confidence you have in an engine's evaluation. |
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Nov-16-18
| | AylerKupp: <<centralfiles> So in conclusion what does the engine say about the 20.Bd5 line? DEAD EQUAL!! > Remember that an evaluation of <Equal> (which I consider to be [ ± 0.49]) means, it means that both sides have <equal chances>, not that the position will necessarily end up in a draw, although that's probably the most likely result. But you have just finished saying that the engines can't see deep enough in these positions, so how can you conclude that the position is therefore a draw <in all possible lines> if you don't really have confidence in the engine's evaluation? And I don't know about you, but to me that's what <conclusively> means. And that's the claim being made for 19...Rf6. <But how long would it take for the engine to see this at move 20.???? Hard to answer definitively of course, but seeing as so many of the moves were far down the engines list of its top choices and were initially evaluated very poorly by the engine, it would take several days at the very least and probably much longer for an engine running at move 20 to see this far.> You have absolutely no valid basis that I can see for making that statement. In a complex position such as this one the engine(s) ranking of the moves can change from ply to ply. So it can take an engine only one ply to change its ranking of the moves completely. How long it takes it to complete a one-ply analysis depends on the search depth, since the time to complete one ply of analysis increases exponentially according to the search depth. But, if you want to find out a definitive answer, see one of my later posts. Spoiler alert: Less than 1 hr 15 mins on a relatively slow computer using Stockfish 9. <The power of hindsight <kwid's provided lines> and sliding is far greater than days or even weeks of computer time.> Agreed. That's something that I haven't attempted to do because I wasn't asked to do it. But that's what I offered to do in Team White vs Team Black, 2017 (kibitz #3939), to have <kwid> (or you, or anyone else) start and analysis with 20.Bd5 and I would do something similar to what I did after 20.Rb1, run a multi-engine analysis overnight to see whether the move that the engines suggest as best is the same move that the human analysis suggests is best. If it is, then I would proceed to have the engines analyze the next move in the analysis. If it isn't, then either consider doing a new analysis starting with the move that the engines suggest is best or do some forward sliding to validate the engines' analyses and eliminate/reduce the impact of the horizon effect. |
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Nov-16-18
| | AylerKupp: <<centralfiles> As far as engine tournaments go: In this kind of situation where we are primarily trying to figure out if a certain move draws with best play it's hard to see any value to them at all.> The only value I see is if we can't reach a definitive conclusion about the game's result after a certain move, something that I believe we can't reach in this game. Then possibly the next best thing is to determine which move gives the statistically best practical chance to achieve the desired result. For that I don't know how many games would be needed to achieve a statistically significant result. If anyone can help me calculate that, I would be greatly appreciative. I also don't know what the time control should be. I want to be able to start each game in the early evening and finish NLT mid-morning. I was able to accomplish that by playing 2 games at a time control of 40 moves in 2 hours and 20 moves every hour afterwards. I can double the time to 40 moves in 4 hours and 20 moves every 2 hours afterwards. This would restrict me to running only one game overnight and, of course, double the time needed to run the number of games needed. But, given that we had 2 days to consider the move to make, will the results acquired by a 40 moves in 4 hours, etc. be considered credible in accepting the results compared to spending 2 days on each move? That's a subjective question. But I'm not willing to either have the games take longer or overnight or conduct any engine vs. engine games if the results of that set of games are not going to be considered conclusive. <<They seem most useful in complex unclear positions with many good ideas for both sides where we are trying to evaluate who has the better practical chances, not if one side is objectively "won". Judging from your last post you probably mostly agree here> Yes, I agree, and I would add "not if one side is objectively won, lost, or if the game is drawn". Because I definitely agree that many of the positions arising in this game, either the actual positions or positions resulting from analysis of alternative lines, are definitely complex and unclear. And that's one reason why it's so difficult to reach conclusive results with straightforward analysis, either human-based or computer-based. |
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Nov-16-18
| | AylerKupp: <<central files> Concerning Hamppe vs Meitner, 1872 I did an extensive analysis of it starting at Hamppe vs Meitner, 1872 (kibitz #216) and Hamppe vs Meitner, 1872 (kibitz #250) in response to a request for an opinion from <chessgames.com> as to the desirability of using this game as the basis for the first Thematic Challenge. And I think they learned their lesson, they've never asked me for a comment ever again. :-) And, given that you're talking abut the Immortal Draw and we're considering whether 19...Rf6 leads to a draw, I think that your mention of that game meets the 6-degree of separation test as far as being on-topic. :-) Maybe that should be an official criteria for <chessgames.com> to determine whether a post is on-topic or not? As far as Stockfish's aggressive search tree pruning, I'm philosophical about it. In life you seldom get something for nothing and chess engines are not exempt from that. Given that as a result of its aggressive search tree pruning Stockfish reaches substantially deeper search depths than, say, Houdini and Komodo. Yet Stockfish's head-to-head game results are not substantially better than Houdini's and Komodo's. So I would be forced to conclude 2 things: (1) Both approaches are equally valid for practical purposes, Stockfish's aggressive search tree pruning and its resulting ability to reach deeper search depths vs. Houdini's and Komodo's less aggressive search tree pruning and their resulting inability to achieve equivalent search depths. The two seem to balance with respect to reaching their high ratings. (2) You need to let Stockfish reach a deeper search depths than either Houdini or Komodo in order to have similar confidence in its evaluations. That's why I alternatively laugh and groan when I see a site like <chess24.com> run a Stockfish analysis to d=24 and then many people (including some of the commentators) attach great (or for that matter, any) significance to its evaluations. |
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Nov-16-18
| | AylerKupp: <<centralfiles> A propos item (2) in my previous post and my earlier spoiler alert, here are the results of a Stockfish analysis in my even older and slower computer (32-bits!) using only 2 threads and a 512 MB hash table after 20.Bd5 at d=36: 1. [+0.90]: 20...Kd8 21.Ne4 Rxf4 22.Nexd6 Bg4 23.Qd3 Ne5 24.Qxh7 Kd7 25.Bxb7 Raf8 26.hxg4 Nxg4 27.g3 Nf2+ 28.Kg2 Qg5 29.Nc8 Rxc8 30.Bxc8+ Kxc8 31.Qg8+ Kd7 32.Nxa7 Bxa7 33.Qa8 Ra4 34.Qb7+ Kd8 35.Rad1+ Nxd1 36.Rxd1+ Bd4 37.Rxd4+ Rxd4 38.Qb6+ Ke8 39.Qe6+ Kd8 40.cxd4 e2 41.Qxe2 Qd5+ 42.Kh3 Qxd4 43.Qe6 Kc7 44.a3 Qc3 45.Qa6 Qd4 46.a4 Qe4 47.Qb5 Qe6+ 48.g4 2. [+1.10]: 20...a6 21.Nd4 Kc7 22.Qb3 Nxd4 23.cxd4 Bxd4 24.Rac1+ Kb8 25.Ne4 Ka7 26.Nxf6 gxf6 27.Rc4 Bc5 28.Re4 Qd8 29.R4xe3 Bxe3 30.Qxe3+ Qb6 31.Qe7 Qd4 32.Qxd6 Bf5 33.Re7 Rb8 34.Qc6 Qb6 35.Qc3 Qd6 36.Qe3+ Qb6 37.Qg1 Qxg1+ 38.Kxg1 Kb6 39.g4 Kc5 40.Bxb7 Bd3 41.Kf2 a5 42.Rd7 Bc4 43.a3 h6 44.f5 a4 45.Ke3 Bb5 46.Rh7 3. [+1.28]: 20...Rxf4 21.Be6+ Kd8 22.Qd5 h6 23.Nf7+ Rxf7 24.Bxf7 Bc5 25.Rad1 Qe5 26.Qf3 Qf5 27.Qxf5 Bxf5 28.Nd4 Bxd4 29.cxd4 Be4 30.d5 Ne5 31.Rxe3 Nxf7 32.Rxe4 Ne5 33.Kh2 b6 34.Rc1 Rc8 35.Rxc8+ Kxc8 36.Re3 Kb7 37.Rb3 a6 38.Kg3 b5 39.Kf4 g6 40.Ke4 Kb6 41.Rc3 Nc4 42.Rc1 Kc5 43.Rc3 4. [+2.56]: 20...Ke8 21.Qf3 Bd7 22.Rad1 Ne5 23.Nxd6+ Qxd6 24.Qh5+ g6 25.Qxh7 Qe7 26.fxe5 Qxh7 27.Nxh7 Rf2 28.Nf6+ Ke7 29.Bxb7 Rd8 30.Nd5+ Ke8 31.Nxb6 axb6 32.Rxe3 Bf5 33.Bd5 Rf4 34.Bf7+ Ke7 35.Rxd8 Kxd8 36.Bb3 Ke7 37.Kh2 Rf2 38.Kg3 Rb2 39.h4 b5 40.Kf3 Be6 41.g4 Bxb3 42.axb3 Rxb3 43.Kf4 Ke6 44.Rd3 b4 45.Rd6+ Ke7 46.cxb4 5. [+3.17]: 20...h6 21.Ne4 Ke8 22.Nxf6+ Qxf6 23.Bxc6+ bxc6 24.Nxd6+ Kf8 25.Nc4 Kg8 26.Nxe3 Be6 27.Qd6 Rf8 28.Qxc6 Kh8 29.Nc4 Bxc4 30.Qxc4 Qxf4 31.Qxf4 Rxf4 32.Rad1 Rc4 33.Rd3 Ra4 34.Re8+ Kh7 35.Re7 Rxa2 36.Rdd7 Kg6 37.Rxg7+ Kf6 38.Rgf7+ Ke6 39.Rde7+ Kd6 40.Re1 Kc5 41.Rf6 Kc4 42.Rxh6 Kxc3 43.Rf1 Rf2 44.Rc6+ Kb4 45.Rxf2 Bxf2 So it <IS> possible for at least Stockfish to consider 20...Kd8 as its best response to 20.Bd5 but admittedly it took it about 1 hr 8 mins to reach that conclusion in my archaic computer. And, since this is a complex position, the move rankings changed from ply to ply: Ply PV=1 PV=2 PV=3 PV=4 PV=5
20 ...Rxf4 ...Kd8 ...Ke8 ...a6 ...Rb8
21 ...Rxf4 ...a6 ...Kd8 ...Rb8 ...Ke8
22 ...Rxf4 ...a6 ...Kd8 ...Ke8 ...Rb8
23 ...Rxf4 ...a6 ...Kd8 ...g6 ...Ke8
24 ...Rxf4 ...a6 ...Kd8 ...g6 ...Rb8
25 ...Rxf4 ...a6 ...Kd8 ...g6 ...Ke8
26 ...Rxf4 ...a6 ...Kd8 ...g6 ...Ke8
27 ...a6 ...Rxf4 ...Kd8 ...g6 ...Ke8
28 ...Rxf4 ...a6 ...Kd8 ...g6 ...Ke8
29 ...a6 ...Rxf4 ...Kd8 ...g6 ...Rb8
30 ...a6 ...Rxf4 ...Kd8 ...g6 ...Ke8
31 ...a6 ...Rxf4 ...Kd8 ...g6 ...Ke8
32 ...a6 ...Rxf4 ...Kd8 ....Ke8 ...h6
33 ...a6 ...Rxf4 ...Kd8 ....Ke8 ...Rb8
34 ...Rxf4 ...a6 ...Kd8 ....Ke8 ...Rb8
35 ...Rxf4 ...a6 ...Kd8 ....Ke8 ...h6
36 ...Kd8 ...a6 ...Rxf4 ....Ke8 ...h6
So, when stopping an engine analysis at an arbitrary point in time (I stop my analyses when I run out of either time or patience, or both), it's important to look at the history of move rankings to see if they have stabilized. In this case they clearly haven't, and since I ran out of both time and patience, I stopped the analysis when I got the results I wanted to show. :-) But, at least to me, given the data above, Stockfish 9's move rankings are not (yet) reliable at d=36. |
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Nov-16-18
| | AylerKupp: <<kwid> But we leave now in the "Bean Counter" times grinding out variations by the numbers with no room for art anymore.> Sad but true. It all depends on the relative value that you place on art and accuracy. As much as we usually admire a spectacular attack involving several sacrifices, its enjoyment for some of us is diluted if it turns out that the defender did not play the best responses. Oh well, Sic Transit Gloria Mundi. And, when I first read your post, I thought you said "with no room for <fart> anymore". I'm glad you didn't say that or I would have been truly depressed, not to mention constipated. :-) |
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Nov-16-18
| | AylerKupp: <<kwid> <Summary of White's choices after 24...Rxb5>
After 24...Rxb5 we reach this position:
click for larger viewNow that my previous "distractions" are out of the way, here is a summary of 3 engines' evaluations, sorted in order of descending Ratings-Weighted Average (RWAvg) since it is White's move. Again, a relatively rare agreement with regards to the top 5 moves but, by chance, not 100% agreement as to their move rankings. Clearly White must recapture so only 25.Rxb5 or 25.Bxb5 should be given serious consideration, and the engines assess that White's <and> Black's best approach after 25.Bxg5 is to seek a draw by repetition. But I asked the engines to display their "top" 5 moves and they obediently complied. White's Houdini 6 Komodo 12.1 Stockfish 9
Move d=27 d=30 d=44 <Avg> <RWAvg> <TrueRank>
---------- ---------- ----------- ---------- ---------- ----------- -----------
25.Rxb5 [+0.80] [+0.68] [+0.84] <[+0.77]> <[+0.77]> <1>
25.Bxb5 [0.00] [0.00] [0.00] <[0.00]> <[0.00]> <2>
25.Nxd6 [-4.90] [-4.96] [-6.77] <[-5.54]> <[-5.56]> <3>
25.Ra1 [-5.42] [-5.19] [-7.01] <[-5.87]> <[-5.89]> <3>
25.Bb3 [-5.71] [-5.26] [-7.01] <[-5.99]> <[-6.00]> <3> True Rank: 1 = [ 25.Rxb5 ]; 2 = [ 25.Bxb5 ]; 3 = [ 25.Nxd6, 25.Ra1, 25.Bb3 ] And here is a summary of how the 3 engines ranked their top 5 moves, without regard for the value of the evaluation. White's Houdini 6 Komodo 12.1 Stockfish 9
Move d=27 d=30 d=44 <AvgRank> <TrueRank>
---------- ---------- ----------- ---------- ---------- -----------
25.Rxb5 1 1 1 <1.0> <1>
25.Bxb5 2 2 2 <2.0> <2>
25.Nxd6 3 3 3 <3.0> <3>
25.Ra1 4 4 4 <4.0> <4>
25.Bb3 5 5 4 <4.7> <4> True Rank: 1 = [ 25.Rxb5 ]; 2 = [ 25.Bxb5 ]; 3 = [ 25.Nxd6 ]; 4 = [ 25.Ra1, 25.Bb3 ] |
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Nov-16-18
| | AylerKupp: <kwid> Here is the current state of the comparison through 24.Ne4 between the moves in your initial analysis in Team White vs Team Black, 2017 (kibitz #3860). Analysis PV=1 PV=2 PV=3 PV=4 PV=5
----------- ------- ------- ------- ------- ------- <20.Rb1> 20.Bd5 20.Qd3 20.f5 <20.Rb1> 20.Qf3 <20...Kd8> <20...Kd8> 20...h6 20...g6 20...h6 20...Bc5 <21.Qd5> <21.Qd5> 21.Qh5 21.Qf3 21.Bd5 21.Nxh7 <21...Bd7> <21...Bd7> 21...a6 21...g6 21...Rf5 21...h6 <22.Red1> <22.Red1> 22.Nf7+ 22.Ne4 22.Qg8+ 22.Nxh7 <22...g6> <22...g6> 22...Rxf4 22...Kc8 22...Na5 22...Rf5 <23.Ne4> <23.Ne4> 23.Nxd6 23.a4 23.Be2 23.a3 <23...Rf5> <23...Rf5> 23...Be6 23...Rxf4 23...Bc5 23...Re6 <24.Qd3> <24.Qd3> 24.Qg8+ 24.Qxd6 24.Nbxd6 24.Qxf5 <24...Rxb5> <24...Rxb5> 24...Rh5 24...Ke8 24...Rxf4 24...d5 <25.Rxb5> <25.Rxb5> 25.Bxb5 25.Nxd6 25.Ra1 25.Bb3 <25...Kc7> (TBD) |
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Nov-16-18
| | AylerKupp: <kwid>, <centralfiles> So now I am at a crossroads as to what to do. Here are some options as I see them: (1) Continue analyzing the moves in the main line posted Oct-08-18 with Black's response to 25.Rxb5 through Black's response to 27.Nxd6. Afterwards continue the analysis of White's response to Black's next move in this line, 27...Rf8. (2) Continue as in (1) above but switch to analyzing White's response to 27...Rf8, the first move in the analysis posted Oct-19-18 after 27.Nxd6 that diverges from the initial analysis posted Oct-08-18. (3) Analyze White's responses to 27...Rf8 and Black's responses to 28.Be2, but then switch to analyzing White's responses to 28...a6, the first move in the analysis posted on Nov-12-18 that deviates from the second analysis posted on Oct-19-18. (4) Wait until <kwid> or someone else develops an analysis main line after 20.Bd5 and begin analyzing Black's responses to that. (5) Stop, recognizing and accepting that this approach will not achieve the goal of conclusively indicating that 19...Rf6 leads to a draw for Black. (6) Other ???
Think about it. I have at least a week since I will be out of town for the Thanksgiving holiday and will not be working on this while I'm away. |
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| Nov-16-18 | | diceman: <AylerKupp:
Ply PV=1 PV=2 PV=3 PV=4 PV=5
20 ...Rxf4 ...Kd8 ...Ke8 ...a6 ...Rb8
21 ...Rxf4 ...a6 ...Kd8 ...Rb8 ...Ke8
22 ...Rxf4 ...a6 ...Kd8 ...Ke8 ...Rb8
23 ...Rxf4 ...a6 ...Kd8 ...g6 ...Ke8
24 ...Rxf4 ...a6 ...Kd8 ...g6 ...Rb8
25 ...Rxf4 ...a6 ...Kd8 ...g6 ...Ke8
26 ...Rxf4 ...a6 ...Kd8 ...g6 ...Ke8
27 ...a6 ...Rxf4 ...Kd8 ...g6 ...Ke8
28 ...Rxf4 ...a6 ...Kd8 ...g6 ...Ke8
29 ...a6 ...Rxf4 ...Kd8 ...g6 ...Rb8
30 ...a6 ...Rxf4 ...Kd8 ...g6 ...Ke8
31 ...a6 ...Rxf4 ...Kd8 ...g6 ...Ke8
32 ...a6 ...Rxf4 ...Kd8 ....Ke8 ...h6
33 ...a6 ...Rxf4 ...Kd8 ....Ke8 ...Rb8
34 ...Rxf4 ...a6 ...Kd8 ....Ke8 ...Rb8
35 ...Rxf4 ...a6 ...Kd8 ....Ke8 ...h6
36 ...Kd8 ...a6 ...Rxf4 ....Ke8 ...h6 > Is it part of your software (or maybe custom programming by you?) that you can track PV moves vs ply depth? |
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| Nov-16-18 | | kwid: In the Rb1 line it may well be better to back solve from the draw position shown below to see if the engines can improve this line. <19. Nb5 Rf6 20. Rb1 Kd8 21.Qd5 Bd7 22. Red1 g6 23. Ne4 Rf5 24. Qd3 Rxb5 25. Rxb5 Kc7> 26. Qxd6+ Qxd6 27. Nxd6 Rf8 28. Be2 a6 29. Rb2 Rxf4 30. Nxb7 Rf2 31. Nd6 Ne5 32. Ne4 Rf4 33. Ng5
h6 34. Nf3 Nxf3 35. Bxf3 Bb5 36. Rb4 Rc4 37. a4 Rxb4 38. cxb4 Bxa4 39. Rc1+ Kd6
40. Be2 Bb5 41. Bxb5 axb5 42. g3 Bd4 43. Kg2 Bb2 44. Rc8 Ba3 45. Rd8+ Ke6 46.
Re8+ Kf6 47. Rxe3 Bxb4 48. Rf3+ Ke7 49. Rb3 Bd2 50. Rxb5 h5 51. Kf3 Kf6 52.
Rb6+ Kf7 53. Ke4 Be1 54. g4 hxg4 55. hxg4
click for larger view |
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| Nov-17-18 | | kwid: <AylerKupp:> To close out the discussion if Rf6 holds I searched in support of the white side and could not come up with any winning lines.
For example:
19. Nb5 Rf6 20. Rb1 Kd8 21. Qd5 Bd7 22. Red1 g6 23. Ne4 Rf5 24. Qd3 Rxb5 25. Rxb5 Kc7 26. Qxd6+ Qxd6 27. Nxd6 Rf8 28. Be2 a6 29. Rb2 Rxf4 30. Nxb7 Rf2 31. Nd6 Ne5 32. Ne4 Rf4 33. Ng5 Rf2 (33... h6 34. Nf3 Nxf3 35. Bxf3 Bb5 36. Rb4 Rc4 37. a4 Rxb4 38. cxb4 Bxa4
39. Rc1+ Kd6 40. Be2 Bb5 41. Bxb5 axb5 42. g3 Bd4 43. Kg2 Bb2 44. Rc8 Ba3 45. Rd8+ Ke6 46. Re8+ Kf6 47. Rxe3 Bxb4 48. Rf3+ Ke7 49. Rb3 Bd2 50. Rxb5 )
click for larger view34. Rf1 h5 35. Ne4 Rxf1+ 36. Bxf1 Bf5 37. Rb4 a5 38. Rb5 Nd7 39. Ng5 Nc5 40. Be2 h4 41. c4 a4 42. g3 hxg3 43. Kg2 Bd7 44. Rb4 Na6 45. Rb1 Ba5 46. Kxg3 Nb4 47. a3 Nc2 48. Rb2 Nxa3 49. Ne4 Kc6 50. Ra2 Bb4 51. Kf3 Bxh3 52. Kxe3 Bf5 53. Bd3 Bf8 54. Kf4 Be7 55. Be2 Bf8
click for larger view |
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| Nov-17-18 | | centralfiles: <AK> I am indeed surprised your old machine managed to get that far down the line in only a little over an hour-though when i said at least days i meant until it sees it closer to dead equal at 0.00 as it does after sliding. I think your CPU speed is a bigger facter than age of your OS etc...
If your'e using an older desktop cpu like an Intel IS-7 2nd gen or something like that, they are still much faster than a modern i5-7200u https://cpu.userbenchmark.com/Compa... |
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| Nov-17-18 | | centralfiles: <AK> As for Hamppe vs Meitner, 1872 I would think Stockfish 9s failure to find the draw until it is literally staring you in the face(considerably worse than stockfish 8) reflects on a serious flaw in the "improved" pruning. |
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| Nov-17-18 | | centralfiles: <<AylerKupp:> To close out the discussion if Rf6 holds...> I would frame the argument as follows:
If none of the computer lines actually lead to wins for white nor are strong humans able to find ideas where it is at least unclear if white might be able to force a win.
Then why would we assume that white might be winning after 19...Rf6?
Isn't the logical conclusion here an overwhelmingly likely draw with best play?
How can we even compare this to 19...h6 when no one yet has been able to show a way where it is even a strong possibility that black draws? Can we "conclusively" say its a draw, of course not, but even the initial starting position cannot "conclusively" be shown to be a draw... |
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Kibitzing
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