< Earlier Kibitzing · PAGE 3 OF 3 ·
|Apr-07-09|| ||agb2002: The fact that three strong regulars tried the same move 34... Qa1# cannot be a mere coincidence but a clue of the existence of a baleful influence (just paraphrasing http://www.cs.berkeley.edu/~wkahan/...) of CG's rating (stars) upon the kibitzer skills.|
Let A be the event that the kibitzer makes a mistake at (as soon as) the fifth ply, B the event that the kibitzer is influenced by CG's rating and C its complementary event, that is to say, the kibitzer is not influenced by CG's rating.
Then, if we can estimate the probability of B, C, A/B, that is, the event of making that mistake under the influence of the assigned rating, and A/C, the event of making that mistake due to other causes, it is possible to work out the probability of B/A, the event of being under the influence of CG's rating knowing that the mistake was made by applying Bayes' theorem:
P(B/A) = P(A/B)*P(B) / [P(A/B)*P(B) + P(A/C)*P(C)]
I've tried a few estimates and always had a result very close to 1. (No criticism against CG intended, just trying to understand curious facts).
|Apr-07-09|| ||xrt999: after 33.Ka3 Rxc2 34.Qe8+ Kh7 35.Qg6 Kg8 (or Kh8) 36.Re8 is indeed checkmate.
So, as you point out, 33...Ra5+ and white has no other move than 34.Qa4 Rxa4 35.Kxa4 Rd4+|
|Apr-07-09|| ||Marmot PFL: This tournament was never finished because of World War I. Mieses was in last place at the time so it probably meant little to him anyway. Breyer might have moved up but did get some prize money for 4th(?) place. Alekhine was way ahead of everyone but was interned in Mannheim with the other Russians. Marshall was allowed to leave but the railroad lost all his luggage.|
|Apr-07-09|| ||SuperPatzer77: <xrt999> <...So, as you point out, 33...Ra5+ and white has no other move than 34.Qa4 Rxa4 35.Kxa4 Rd4+>|
<xrt999> 33...Ra5+, 34. Qa4 Rxa4+, 35. Kxa4 Rxc2 (much better than 35...Rd4+) -- that gives Black a big advantage with one queen up.
<xrt999> It is because 35...Rd4+ 36. Ka3 (that helps White escape the checkmate).
So, 35...Rxc2 is a lot better than 35...Rd4+.
|Apr-07-09|| ||Frankly: What seemed simpler, and also appears to win as well, was ...Rd2 33. Rc2 (forced); Rxc2+ and then Kxc2 (lest rook for queen) and then Qxc3+, after which mate too. Anything wrong with that?|
|Apr-07-09|| ||agb2002: <Frankly: What seemed simpler, and also appears to win as well, was ...Rd2 33. Rc2 (forced); Rxc2+ and then Kxc2 (lest rook for queen) and then Qxc3+, after which mate too. Anything wrong with that?> 34.Qxc2 and White is better.|
|Apr-07-09|| ||beenthere240: In the 33...Qa1# line, I thought the rook on d2 was protected by the invisible bishop on g5.|
|Apr-07-09|| ||Once: One of the drawbacks of coming late to a puzzle is finding something interesting to say that has not already been well aired.|
So let's rewind a few moves and put ourselves in white's shoes. It is white to play ... and lose.
click for larger view
Black's e4 pawn is a potential game winner ... for either player! As a passed pawn, black dreams of ramming it up the board to promotion. But as an isolated passed pawn, white looks forward to overpowering it, winning it and then converting his pawn plus into an endgame win.
Black's previous move 29...Rfd8 probably gave white a clue that something was not quite right. Instead of protecting his e4 pawn, black doubles rooks on the d file. Then white spots the trick: 30.Qxe4 loses to 30...Rd2+.
So white needs to prepare Qxe4. After all, the pawn isn't going anywhere. So he possibly imagines a reorganisation of his troops ... 30. Rc1 to protect the c3 pawn, 31. Kb1 to unpin the c3 pawn, 32. c4 to protect the c4 pawn. Then we can think about Qxe4 or perhaps we first want to trade off the rooks. Easy peasy.
Or maybe he dreams of playing Rc2 either before or after the Rd2+ trick.
30. Rc1 Rxc5
click for larger view
Now white miscalculates. Black has undoubled rooks on the d file, apparently releasing some of the tension. White thinks he can defend against 31...Rd2+ by playing 32. Rc2.
click for larger view
This was the position that white expected after playing 31. Qxe4. The rook check will not have come as a surprise to him ... he has been guarding against it for the past couple of moves. What he has missed is that the Rc2 is pinned and that Black wins with the killer 32...Qxc3+.
The morale of the story is clear. Examine all checks and captures, including those by your opponent! To be fair to white, at move 30+, we are probably into time trouble territory.
|Apr-07-09|| ||YouRang: I saw 31...Rd2+ pretty quickly since the *deflection with check* tactic is seen pretty frequently. However, the interesting wrinkle is that white can *seemingly* deal with the check and resist the deflection with 32.Rc2.|
But then, it's not too hard to see that 32...Qxc3+! exploits the pinned Rc2. White must play 33.Kb1 (33.Kc1? Qa1#). But now, 33...Rd1+ 34.Rc1 Qxc1#. Good Tuesday puzzle.
|Apr-07-09|| ||patzer2: For today's Tuesday puzzle solution, Black's 31...Rd2+! uses a deflection to attack the guard and set up a winning attack on the pinned piece after 32. Rc2 Qxc3+!|
|Apr-07-09|| ||HSOL: I found it a pretty nice use of pins. Always fun to pull something similar off in your own games.|
|Apr-07-09|| ||SuperPatzer77: <YouRang: I saw 31...Rd2+ pretty quickly since the *deflection with check* tactic is seen pretty frequently. However, the interesting wrinkle is that white can *seemingly* deal with the check and resist the deflection with 32.Rc2.
But then, it's not too hard to see that 32...Qxc3+! exploits the pinned Rc2. White must play 33.Kb1 (33.Kc1? Qa1#). But now, 33...Rd1+ 34.Rc1 Qxc1#. Good Tuesday puzzle.>|
You've overlooked 33. Kc1 Qxa1+ (not mate) 34. Kxd2 (that costs Black a rook). Can't you see that the Black Rook on d2 is unprotected????
After 33. Kc1, the correct move is 33...Qxc2+!, 34. Qxc2 Rcxc2+, 35. Kb1 Rxe2 (Black wins two rooks and mates soon)
<YouRang> You should take a look at the Black Rook on d2 that is unprotected.
|Apr-07-09|| ||eblunt: < xrt999:
do you mean Ra5+? >
Yes of course, thanks ... told you I was going mad !
|Apr-07-09|| ||TheChessGuy: Did Gyula Breyer ever play the C95 Spanish? I can't find any games where he uses his eponymous variation.|
|Apr-07-09|| ||YouRang: <SuperPatzer77><You've overlooked 33. Kc1 Qxa1+ (not mate) 34. Kxd2 (that costs Black a rook). Can't you see that the Black Rook on d2 is unprotected????>|
Yes, of course I can that the rook on d2 in unprotected! (...now that you've mentioned it).
Haste makes waste. :-(
Hopefully, had I been really playing these moves, I would have caught myself before playing Qa1+??. Yes, Qxc2+ is the correct move as you say. Thanks.
|Apr-07-09|| ||Peter Nemenyi: We're now up to four posters who've seen the nonexistent mate with 33...Qa1+, which must mean something. Is there a strong subconscious tendency to assume that two rooks on open or semi-open files are lined up on the same file in the usual way, and so protect each other?|
|Apr-07-09|| ||pankajdaga: Saw it in less than 5 seconds. Geez...these pattern recognition exercises really do work!|
|Apr-07-09|| ||johnlspouge: < <Peter Nemenyi> wrote: We're now up to four posters who've seen the nonexistent mate with 33...Qa1+, which must mean something. Is there a strong subconscious tendency to assume [snip] >|
We mistaken posters might be recalling that the d-file was covered by a "safe" R at the combination's beginning, so then we saw a semi-epaulette mate with the Q at a1. It is significant that the posters making the mistake are all experienced and probably abbreviate their analysis with pattern recognition.
Another factor might be that this is Tuesday, so there is insufficient complexity to force review of the variations. Later in the week, I often catch visualization errors when I think about secondary variations.
|Apr-07-09|| ||Domdaniel: <We're now up to four posters who've seen the nonexistent mate with 33...Qa1+, which must mean something. Is there a strong subconscious tendency to assume that two rooks on open or semi-open files are lined up on the same file in the usual way, and so protect each other?>|
Or perhaps that a piece which was previously immune from capture has some kind of permanent immunity? It really is very strange, the way that rook keeps hanging. We may have discovered a bug in the human chess program.
|Apr-07-09|| ||DarthStapler: Got it|
|Apr-07-09|| ||WhiteRook48: 31...Rd2+ was easy!!|
|Apr-07-09|| ||OhioChessFan: Easier than yesterday.|
|Apr-07-09|| ||Once: <Domdaniel: We may have discovered a bug in the human chess program.>|
Fully agree, and nicely put. I have a theory that as we get older and more experienced, we tend to simplify more. So we stop truly looking at things and instead we classify them into easy to manage categories. Where a child would look at something with open eyes of wonder, we greybeards hardly notice things.
I find it incredibly illuminating to follow the thought patterns of my 8 year old son. He sees things that I don't give a second glance to.
The Rd2 has been protected successively by the Rd8, the threat of QxQ and the Qc3. So the more experienced amongst us classify it as "protected" and don't notice that each of the protections has disappeared.
I suppose that's one of the drawbacks of experience - we tend to rely on shortcuts like pattern recognition and categorisation. Perhaps we should all try to look through the eyes of children and patzers once in a while?
|Apr-07-09|| ||CHESSTTCAMPS: <Once:> wrote <Fully agree, and nicely put. [snip]> |
I don't want to beat this poor horse into glue, but I partly agree with each of the three previous posts on the subject. I (along with 3 others) made this error and I can recall the general sequence of my thoughts. Originally, I was going to post the solution as 31.... Rd2+! 32.Rc2 Rxe2(?) 33.Rxe2(?) Qxc3+. In the course of writing this up, I realized that 33.Qxe2 cooked it, so I quickly worked out the correct 2nd move 32...Qxc3+! and the correct follow-ups, including 33.Kc1 Qxc2+. It was when I actually wrote out the final piece of the post that I "saw" and wrote up the Qa1# hallucination.
I think there were a few things going on here:
1. I'd found the two key moves Rd2+ and Qxc3+, so there was a tendency to relax and treat the rest of the solution as an afterthought. This is close to what fellow hallucinator <Johnlspouge> said in his last post.
2. Trying to present the completion of the solution in a neat little package, it was desirable to find a one move answer to meet each legal white response to Qxc3+. Qa1# is an aesthetically pleasing finish, so in a way, the wish was father to the thought.
3. I've had other instances of "retained image" in my solutions, including the March 29 puzzle, where one supporting line of analysis included a phantom rook that had already moved to another square. However, that involved a line of analysis that was many plies deeper. How could I possibly forget from one move to the next that the Rd2 was no longer protected? That's where I think that <Domdaniel> and <Once> both have made excellent points.
|Apr-09-09|| ||SuperPatzer77: <xrt999> <...So, as you point out, 33...Ra5+ and white has no other move than 34.Qa4 Rxa4 35.Kxa4 Rd4+>|
After 32...Qxc3+! White's another try is 33. Ka3 Ra5+, 34. Qa4 (forced) Rxa4+, 35. Kxa4 Rxc2! -- It's much stronger than 35...Rd4+ because if White declines the rook trade, he will face the inevitable checkmate. Otherwise, White reluctantly has to trade the rook to avoid being mated.
Black actually forces simplicity and the rook trade with 35...Rxc2! because White has no major and minor pieces left on the board when Black has a one-queen advantage.
<xrt999> 35...Rxc2! 36. Rxc2 (forced) Qxc2 , so that's why 35...Rxc2! is much stronger than 35...Rd4+. Did you get it, <xrt999>?
I mean that 35...Rxc2! 36. Re8+?? Kf7 with double attack - forcing White to give up another rook to avoid getting mated. 0-1
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