tag:blogger.com,1999:blog-37675897.post9171619904934011962..comments2023-12-28T02:11:22.501+00:00Comments on The Streatham & Brixton Chess Blog: Blue or Red Pill? XVIITom Chivershttp://www.blogger.com/profile/09850710685193416732noreply@blogger.comBlogger15125tag:blogger.com,1999:blog-37675897.post-70963946763995063952013-04-10T01:31:28.437+01:002013-04-10T01:31:28.437+01:00When I tried Houdini 3.0 on this position it chose...When I tried Houdini 3.0 on this position it chose Rh5 within a few seconds and by the time it got to 30 ply its eval was +3.0.<br /><br />I don't know what version you (Anonymous) was using, but there does appear to be an issue with Houdini 3.0 where if it thinks you don't have a legit copy it gives weird evaluations, especially in the endgame. (I am not accusing you of anything; after buying it I had to download it a second time before its evals made any sense.)Dan Schmidthttp://dfan.org/blog/noreply@blogger.comtag:blogger.com,1999:blog-37675897.post-64181991073634298532013-04-09T18:52:36.641+01:002013-04-09T18:52:36.641+01:00Although, as it happens, it's clearly the only...Although, as it happens, it's clearly the only move.Jonathan Bhttps://www.blogger.com/profile/00293162543015231439noreply@blogger.comtag:blogger.com,1999:blog-37675897.post-83206866066315408192013-04-09T18:50:29.859+01:002013-04-09T18:50:29.859+01:00Apologies, I didn't read your comment properly...Apologies, I didn't read your comment properly.<br /><br />I meant 'in general' you don't have to place the rook on c5. After the specific position that we get after <b>1 Rh5 Kc4</b> I'd certainly trust Nalimov's opinion over mine.Jonathan Bhttps://www.blogger.com/profile/00293162543015231439noreply@blogger.comtag:blogger.com,1999:blog-37675897.post-59448437150679115592013-04-09T18:13:43.555+01:002013-04-09T18:13:43.555+01:00Also, it's not necessary to go to c5 with the ...<i><br />Also, it's not necessary to go to c5 with the rook after 1 Rh5.</i><br /><br />Unless I am missing something, Nalimov disagrees with you.ejhhttps://www.blogger.com/profile/01582272075999298935noreply@blogger.comtag:blogger.com,1999:blog-37675897.post-551413563221832882013-04-09T13:36:47.437+01:002013-04-09T13:36:47.437+01:00Of course AngusF is largely correct but a 30-ply a...Of course AngusF is largely correct but a 30-ply analysis beast is still a behemoth of an assistant for checking variations. As humans we must try to establish underlying concepts and rules-of-thumb for playing out these positions. However as someone who's had access to chess computers for over 30 years I have to say Houdini is incredible. (And I'm only a cheapskate with the free version.) It was able to see mate-in-27 from a random KBNvK position for example.Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-37675897.post-52700851922479057802013-04-09T12:38:01.484+01:002013-04-09T12:38:01.484+01:00engines are rubbish at rook endings so houdini not...<i>engines are rubbish at rook endings so houdini not knowing 1 Rh5 wins doesn't surprise me in the least.</i><br /><br />I suspect that engines aren't that good at endings at all.<br /><br />My guess is that they have little or no algorithms to win/draw endings by technique.<br /><br />Access to tablebases helps though only for positions with a limited number of pieces. (I see that <a href="http://chessok.com/?page_id=27966" rel="nofollow">ChessOK have recently announced access to 7-piece tablebases</a>).AngusFhttps://www.blogger.com/profile/09312254103335063535noreply@blogger.comtag:blogger.com,1999:blog-37675897.post-35740107460317746392013-04-09T10:32:44.184+01:002013-04-09T10:32:44.184+01:00Ps - engines are rubbish at rook endings so houdin...Ps - engines are rubbish at rook endings so houdini not knowing 1 Rh5 wins doesn't surprise me in the least.<br /><br />30 ply is no substitute for technique.Jonathan Bhttps://www.blogger.com/profile/00293162543015231439noreply@blogger.comtag:blogger.com,1999:blog-37675897.post-27665799609695699722013-04-09T10:27:55.683+01:002013-04-09T10:27:55.683+01:00After Rc1 ...Ra8 loses. You should leave it on the...After Rc1 ...Ra8 loses. You should leave it on the b file to stop the pawn advancing.<br /><br />Also, it's not necessary to go to c5 with the rook after 1 Rh5. <br /><br />Sorry for brevity but its not easy to type comments on an iPhone Jonathan Bhttps://www.blogger.com/profile/00293162543015231439noreply@blogger.comtag:blogger.com,1999:blog-37675897.post-40001779217188277052013-04-09T09:56:31.697+01:002013-04-09T09:56:31.697+01:00I have looked it up and I would try to find a rati...I have looked it up and I would try to find a rationalisation for Rh5 instead of Rc1. Distance to the queening square of b8 is always important and Rh5 keeps the King further away once White manages to get the b pawn to advance.<br /><br />When you get these endings in practice, it's almost always against the clock even with a 30 second increment, so knowing what to play without much thought is often necessary.<br /><br />RdCAnonymousnoreply@blogger.comtag:blogger.com,1999:blog-37675897.post-86323778703891432722013-04-09T08:32:50.513+01:002013-04-09T08:32:50.513+01:00The difficult thing is working out how White makes...The difficult thing is working out how White makes progress after 1.Rh5 Kc4 2.Rc5+ Kd4. Obviously I can look it up if I want, but if you don't already know, it's not so easy to see. (Also, one is naturally likely to think - if 2.Rc5 is forced, why not 1.Rc1 putting the rook on the c-file straightaway?)ejhhttps://www.blogger.com/profile/01582272075999298935noreply@blogger.comtag:blogger.com,1999:blog-37675897.post-89188005025228104802013-04-09T02:32:14.268+01:002013-04-09T02:32:14.268+01:00Houdini couldn't see a win after Rh5 analysing...Houdini couldn't see a win after Rh5 analysing to 30-ply. Also in my Rc1 Ra8+ Kb3 Kd5 b5 Kd6 Kb4 Kd7 b6 Rc8 line now Rc5! wins apparently. Back to the drawing board I think.Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-37675897.post-11078122421402344952013-04-08T19:41:25.740+01:002013-04-08T19:41:25.740+01:00Yes, you're all right - although it's inte... Yes, you're all right - although it's interesting to see the different thought processes of getting there.<br /><br />In essence, the defending cut off by one file is not enough for a knight's pawn in it's own half of the board. If the defender is well placed, that is (as the rook and king are here).<br /><br />So 1 Rh5 can't have a down side. It wins, although I think 1 ... Ra8 is a tougher defence than 1 ... Re8.Jonathan Bhttps://www.blogger.com/profile/00293162543015231439noreply@blogger.comtag:blogger.com,1999:blog-37675897.post-47260901455752524302013-04-08T17:55:46.601+01:002013-04-08T17:55:46.601+01:00Rh5, bien sur. It's a general principle in roo...Rh5, bien sur. It's a general principle in rook endings (or so I once read somewhere) that cutting the defending king off on a rank is generally more effective than doing it on files. Besides, as someone said above, Rc1 is a fairly trivial draw - 1...Kd5, and what's White's next move supposed to be?John Coxnoreply@blogger.comtag:blogger.com,1999:blog-37675897.post-20040462550519136722013-04-08T12:42:16.377+01:002013-04-08T12:42:16.377+01:00My recollection from Rosen's book Chess Endgam...My recollection from Rosen's book Chess Endgame Training is that Rc1 is insufficient with the pawn still in White's half of the board. White's king can't move forward to dislodge the rook without dropping the pawn that is too far behind him. I think Black's king just has stay on d5 and d6 so that White can't play Rc5 and then b5.<br /><br />So, given two choices, I guess I'd play Rh5 by process of elimination, although if it is in fact correct I'd have to work out the rest from first principles.Dan Schmidthttp://dfan.org/blog/noreply@blogger.comtag:blogger.com,1999:blog-37675897.post-90496354757396543242013-04-08T11:17:43.987+01:002013-04-08T11:17:43.987+01:00The trouble with Rc1 is that White's progress ...The trouble with Rc1 is that White's progress seems to be slow so that the Black King has time to scuttle back to Kd7 and allow Rc8. For example, Rc1 Ra8+ Kb3 Kd5 b5 Kd6 Kb4 Kd7 b6 Rc8 Rxc8 Kxc8 Kb5 Kb7=<br /><br />After Rh5 Black seems stuffed. The naive Re8 Ka4 Re5 Rxe5 Kxe5 Kb5 Kd6 Kb6 just seems a trivial win and I can't see any real improvements.Anonymousnoreply@blogger.com