< Earlier Kibitzing · PAGE 3 OF 3 ·
|Jun-30-07|| ||Peligroso Patzer: It was not immediately obvious to me why Black could not defend with 35. ... Rd8. With some help from Fritz, I came up with the following continuation (main variation only is given) that wins for White: 35. ... Rd8 36.Qe7+ Kg8 37.Rg1 g5 38.Bxg5 .|
|Jun-30-07|| ||tangobob: Can someone explain to me why the black's rook sac at 35...Rb3+? Why not 35...Rb7 or something else more defensive, looking for the first opportunity to exchange pieces?|
|Jun-30-07|| ||tangobob: <Peligroso> Thanks, you posted while I was writing my post. By the way, I was actually thinking Rc7 not Rb7 (36.Qc8 obviously). Now I think I see that there's no better defense for black than the rook sac 35...Rb3+. This is the part of the puzzle I missed, since I considered Rd1 but thought black could still defend....|
|Jun-30-07|| ||DexterGordon: <tangobob>, so how does White continue after 35...Rc7? Is it as simple as 36. Rd7+ Rxd7 37. Qxd7+ Kg/h8 38. Bh6?|
|Jun-30-07|| ||kevin86: I figured the first four moves-so I guess I got it right.,lol|
Although white ends a piece ahead,there is a great deal of work left (to steal a term from golf). The pawn race is exciting-with black having the Hobson's choice on which pawn he will take-and allow the other to queen.
|Jun-30-07|| ||tangobob: <Dexter> Yes, that's exactly the line that makes me believe that the 35...Rb3+ rook sac is better (coupled with <Peligroso's> analysis...).|
|Jun-30-07|| ||LIFE Master AJ: Problem of The Day
June 30th, 2007.
(White to move, 30.???)
click for larger view
White: Kb1, Qc6, Be3, Re6, Rh1; Pawns - b3, c2, e4, & h2.
Black: Kf7, Qa5, Nf6, Rb8, Rc8; Pawns - a6, c3, e5, g6, & g7.
I spent 5-10 minutes on this problem, however, I did NOT get the solution! (I found the first couple of moves, but went astray later.)
I failed to appreciate the subtle Rd1! (The purpose of this move is to move Black's Rook off c8. Otherwise, Black will have ...RxP/b3+!; followed by ...c2+; winning.)
It looks like Black was forced to play 35...Rd8. (At least, I thought maybe he should.) 35...d8; 36.e7+ g8; (Or 36...h8; 37.xf6+ h7; 38.f7+ h8; 39.g1, winning for White.) 37.g1 g5; 38.xg5!
A very nice problem and a worthy Saturday brain twister. [From one of my favorite players. Many players today are too young to remember that Walter Browne was a terror in the U.S. in the early to late 1970's. At one point, he seemed to win the majority of all the strong swiss tournaments that he entered.]
|Jun-30-07|| ||vik2137: I think Rxf6 gxf6 31 Qd7+ Kg8 32 Rg1 wins too.
f 32...Rb3+ then 33. cxb3 c2+ 34. Kb2 Qc3+ 35. Ka3 Qa5+ 36. Qa4 and white ends up with the extra piece, like in the game
|Jun-30-07|| ||vik2137: any thoughts on that?|
|Jun-30-07|| ||LIFE Master AJ: Jun-30-07 < <vik2137>: I think Rxf6 gxf6 31 Qd7+ Kg8 32 Rg1 wins too.> |
Like many others, you failed to consider 32...Rxb3+; and 33...c2+. (Read a few of the previous posts.)
|Jun-30-07|| ||OneArmedScissor: I got this one.
|Jun-30-07|| ||LIFE Master AJ: White also missed a win on his 26th move ... but it was not easy to find. |
Better was 26.xe7! xe7; 27.xd6!! b5; This might be forced, the alternatives are much worse.
<(For example, Black gets clobbered after: 27...xd6?; 28.d1+ e7; 29.c5+ xc5; 30.xc5+ f7; 31.c7+, and the Rook on b8 is lost.)>
28.e6+ f8; 29.hd1 e8; 30.d8 xh2; 31.c1! a5!?; (This is not good, but the box is already showing a forced mate ... no matter what Black plays.) 32.1d7 xd7; 33.a3+ e7 34.xe7#.
|Jun-30-07|| ||MostlyAverageJoe: <vik2137: any thoughts on that?> 32 ... g5 is worth a look after Rxf6 gxf6 31 Qd7+ Kg8 32 Rg1|
|Jun-30-07|| ||DCLawyer: Point taken, <chessgames.com>. As <al wazir> points out, anyone who saw Rd1 and the fact that the Queen on e6 protects against the counter-sacrifice on b3 probably deserves full credit. Even so, the fact that after 36.Qxb3, Black has two pawns for the piece, and enough play to prolong the game for another 38 moves, suggests that the position is not yet a mathematical win, and might lead true perfectionists to spend more time on this puzzle than necessary. Incidentally, that was not my problem, as I missed both of the ideas mentioned above!|
|Jun-30-07|| ||rodrigochaves: Can anyone please explain the point of 35. Rd1?
isn`t the 7th rank could be covered by Rc7?
35.Rd1 Rc7 36.Rd7+ Rd7 37. Qd7+ and here, if 37.Kg8 we have 38.Bh6 Rxb3+
39.cxb3 c2+ 40.Rxc2 and Qa2+
but im not able, or with patience (or the both) to evaluate if black could force the perpetual.
Can anyone explain the idea behind Rd1 followed by Rc7-Rd7+?
|Jun-30-07|| ||purewal: Black could have drawn the game by playing 55...,Ke2 instead of Rb6+. I played 55...,Ke2 against Fritz and the following line resulted.
|Jul-01-07|| ||MostlyAverageJoe: <LIFE Master AJ> and <Peligroso Patzer> Indeed, the possible response 35. ... Rd8 that you both considered loses quite horribly, probably deserving an exagerrated (++ ) designation :-)|
Hiarcs evaluated 35. ... Rd8 as >6.0 within a second or two, and after a while, with a little of forward/backward analysis, settles on (+25.26).
I verified that the line found in your posts (indeed, initially it appears to be best for the black):
36.Qe7+ Kg8 37.Rg1 g5 38.Bxg5
resulits in a forced mate in 9. Here's the mainline:
38. ... Rxb3+ 39. cxb3 Rd1+ 40. Rxd1 c2+ 41. Kxc2 Qa2+ 42. Kc3 Qa5+ 43. Kb2 fxg5 44. Rd7 Qa2+ 45. Kxa2 g4 46. Qg7# *
|Jul-01-07|| ||MostlyAverageJoe: <myself: The first moves played in the game (except for the wasted move 33) are definitely best for both sides up to 35.Rd1. Now, black has another reasonable response, Rc7, which looks good until the analysis gets 17 plies deep. It definitely would need to be explored if I had time.>|
Since many others mentioned 36 ... Rc7 defense, I did some analysis, coming up with this line that is pretty much best for both sides. The way I do this is run the engine in multi-PV mode, picking the substantially stronger lines, and branching on moves where several similar alternatives occur - then backtrack to mainline after exploring branches and pulling their valuations along during the backtrack. With sufficient memory, this accelerates the exploration of the position immensely, provided that a forcing line exists.
35. Rd1 Rc7 36. Rd7+ Rxd7 37. Qxd7+ Kh8 38. Qh3+ Kg8 39. Qe6+ Kg7 40. Qe7+ Kh8 41. Qxf6+ Kg8 42. Qxg6+ Kh8 43. Bg5 Rb6 44. Bf6+ Rxf6 45. Qxf6+
which ends up in this position (black to move):
click for larger view
Note the overworked black queen. White will now push the h-pawn until the black Q releases the defense on c3 pawn, take it, pick off either the e or the a pawn, and it is an assured win for the white.
|Jul-01-07|| ||tangobob: Wow, <MAJoe>, thanks for that analysis, I knew there was a lot more to analyze with the 35...Rc7 defense. Makes me feel a little better for not seeing that by 35.Rd1 white was in an obviously winning position....|
|Jul-01-07|| ||patzer2: Starting with the demolition sacrifice 30. Rxf6+!!, White puts the Black King on the run long enough to secure a won endgame.|
|Jul-01-07|| ||LIFE Master AJ: <Mostly>
"Indeed, the possible response 35. ... Rd8 that you both considered loses quite horribly,..."
Exactly my point. (I don't think like a machine ... and have never bothered to pretend that I do.) I only analyzed the continuation in question, because I was interested in it ... and therefore, it was possibly that someone else might be as well.
To be honest, unless someone bothers to explain the ideas behind a line, or gives analysis as meticulous as (say) <RandomVisitor>, I find such lengthy analysis boring.
I followed the Candidates Matches quite closely, and even the best players in the world failed to discover the "machine move" at many points ... no one made a big deal out of it.
And most of these guys who are addicted to their boxes can do any real analytical work without them, anyway.
|Jul-02-07|| ||MostlyAverageJoe: <LIFE Master AJ: To be honest, unless someone bothers to explain the ideas behind a line, or gives analysis as meticulous as (say) <RandomVisitor>, I find such lengthy analysis boring.>|
Are you implying, then, that my computer-aided analyses are boring?
|Jul-02-07|| ||LIFE Master AJ: No. More that your comment, <<Indeed, the possible response 35. ... Rd8 that you both considered loses quite horribly, probably deserving an exagerrated (++ ) designation :-) >> was either a joke I did not get, or perhaps too harsh a criticism. |
And that humans do not ... not now, not ever ... play chess like a machine.
|Jul-02-07|| ||MostlyAverageJoe: <LIFE Master AJ> OK, i see. |
Rd8 was one move (of several) that I failed to consider in my first (computer-free) post on page 1, so after you and <Peligroso> have mentioned it as winning for white, I decided to look at the continuation of the line you both mentioned, and had Hiarcs find for me a forced mate (AKA "horribly losing").
I suppose both you and I need to stop looking for criticism where none is implied.
|Jul-02-07|| ||LIFE Master AJ: That's cool with me.
Another point I want to make is many of the lines that the computer wants to look at are not playable, at least, not by (normal) human standards.
For example, when the computer starts playing "suicide chess" to prevent a mate ... the average human will resign before doing this. OR ... let's say the computer wants to give up its Queen as the only defense to a threat ... once more humans won't consider this. (It won't matter if there is even a five-point difference between two lines, any normal human isn't going to consider that for long.)
Another one of my pet peeves is when annotators discover an improvement ... usually with the computer ... and then they assign the old move a question mark. (The "Modern School" of annotation.) To me, this is silly. (A good example in this game was that Browne missed an improvement on his 26th move in this game, see my earlier posts.)
I have annotated hundreds of "older" (pre-computer) games, [not all of them get posted on the Internet]; and the machine has found dozens of improvements. Maybe Browne saw 26.Nxe7 (followed) by Rxd6), but did not analyze it deep enough to see the win.
To me, none of this matters. I much prefer the way humans play chess. Just about every GM game I have examined in recent times - Fritz has found an improvement at some point.
Of course, the search for truth is an entirely different matter. For example, when "RandomVisitor" discovers a new move ... in a heavily analyzed position, where many GM's have looked at the game before ... and discovers a new move, this can be exciting. Its also amazing to see how the computer finds shots a human won't even look at, (unless your name is Kasparov, Fischer or Tal).
And I am beginning to ramble here, I am not even sure if I made my point ... (Peace to you as well.)
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