< Earlier Kibitzing · PAGE 2 OF 2 ·
|Jun-25-10|| ||chrisowen: Lerner holds Dorfman at bay. Rook takes a seat at f2 coaching forwards the pawn. Autonomy of gears shifting doing crunch believe b7 c6 d5 stalls it he steps on the gas and hurridly gets reversed. Whip up Rf8 dead in the water assumption spills out once white treads over.|
|Jun-25-10|| ||kevin86: This one is all about timing. First white seals black to the last two files and then rushes the king in as fast as possible.|
Strategic rook moves are necessary also-finally king and rook can round up the impudent pawn.
|Jun-25-10|| ||dzechiel: <wladimirsky: dzechiel: with all due respect, this position has nothing to due with the old Reti study. ... >|
I stand corrected! I must not have been reminded of this study after all (but it seemed so real at the time!)
|Jun-25-10|| ||YouRang: Well, now that I've looked at the answer, it makes perfectly good sense.|
Right away, stop the black king from opposing the advance of my king. I didn't get the solution, but I got the instruction. Thank you cg.com.
|Jun-25-10|| ||YouRang: <David2009> <...Crafty gives up early (plays g4 and g3)>|
LOL! One of the failings of computers is that they have no concept of human foibles. Consequently, they have a hard time distinguishing a challenging win from an easy win (where "challenging" and "easy" are measured in human terms).
The computer (black) sees that it loses after white plays Rf2! no matter what. It thus concludes that one losing move is as "good" as another, and thus it picks the move that most obviously (to humans) loses.
|Jun-25-10|| ||zooter: This looks more like an endgame study to me than a puzzle.|
71.Rf2 g6 (eventually this has to be played, so why not now? 72.Kb8 Kh7 73.Ra2 followed by Ra7 pinning etc maybe?
I'm not sure. Time to check
|Jun-25-10|| ||zooter: Ok, I got the right idea but for some strange reason thought that the black pawn is moving up the board and needs only 3 moves to queen|
Anyways, the technique is to count the number of squares it takes for the black king+pawn to come to the queening square and the same for white rook + king to guard it
White seems to lose a tempo by moving the rook, but playing 71.Rf2 prevents the black king from opposing the white king
I hope all this is right as I haven't yet checked the kibitz
|Jun-25-10|| ||SpoiltVictorianChild: I love puzzles like this. Difficult, but where the solution is simplistic and logical.|
|Jun-25-10|| ||zooter: Well, Got to hand it to the usual suspects. Who you ask? Smack you in the face and go check the first 2 posts by <dzechiel> and <once>. Come back to me and type it from memory before you proceed elsewhere!|
|Jun-25-10|| ||JG27Pyth: Well, since Dzechiel is getting well-deserved praise for his typically clear and instructive kibbitz... I think it's ok for me to point out that this:
<Dzechiel:When a king moves on the diagonal, he moves 1.4 times farther than when he moves on the rank or file (still one square, but moving on the diagonal is similar to moving one square on the rank followed by one square on the file).>... is completely daft, right? Is it me? Have I failed at perceiving obvious irony? Um, there's no .4's on a chess board, no fractions of a move?! It's all integers, isn't it? |
Soylent green is made of people!
|Jun-25-10|| ||johnlspouge: Friday (Difficult)
K Lerner vs Dorfman, 1980 (71.?)
White to play and win.
Material: R for P. The White Rh2 cannot stop Pg5 alone, so White needs to bring his K to the K-side.
Candidates (71.): Kb7
I knew that I was making a bad assumption somewhere. I see <dzechiel> has some cogent kibitzing.
For some bizarre reason, I reversed the directions of P movement.
|Jun-25-10|| ||turbo231: missed it didn't plant my rook on the f file.|
|Jun-25-10|| ||jfshade: <YouRang:...I didn't get the solution, but I got the instruction. Thank you cg.com.>
Seconded - thanks everybody.|
|Jun-25-10|| ||gofer: <JG27Pyth>, <dzechiel> isn't wrong, just roughly right. It doesn't suite his writing style to write "the square-root of two" and trying to write it mathematically in this editor is not as easy as you might think...|
|Jun-25-10|| ||YouRang: <gofer>, <JG27Pyth> <dzechiel> Re: <1.4 times farther>|
I would add that it's not really the geometric distance that matters here (that is, the distance measured in inches, centimeters or whatever).
What matters is the distance measured in tempos. When the king moves diagonally, it makes progress along two dimensions instead of one, which in effect, makes it move *twice* as fast (compared to moving two times, one dimension at a time).
Of course, this 'tempo' measure of distance is only meaningful if it is necessary for the king to travel along both dimensions (as in the case of this puzzle). If the king merely had to travel from e1 to e8, it could get there using mostly diagonal moves (e.g. zig-zag), but with no benefit over one-dimensional moves.
|Jun-25-10|| ||Once: Well, I agree with <dzechiel>, and not just cos he is a multi-millionaire with a huge mansion, a cool black car and a utility belt :-)|
Let's try explaining it another way. Here's the starting position:
click for larger view
For white to win his king needs to get to the danger zone faster than black. Because white has to travel on the diagonal, he has only one fastest route: Kb7-Kc6-Kd5-Ke4-Kf3 - five moves in total. Any other route is slower.
Meanwhile, black has a choice of routes to the same spot. The quickest, as the crow flies, is Kg6-Kf5-Kg4-Kg3 and that's just four moves.
But unlike white, black doesn't have to go as the crow flies. He can fly to the rhythmn of the vuvuzelas and bend the flight of his jabulani ball. In the same four moves, he can also get there via a parabola - Kf6-Ke5-Kf4-Kg3. Ain't that purty?
And look what happens when white allows black to do this:
71. Kb7? Kf6 72. Kc6 Ke5
click for larger view
Now white can't maintain his direct path. He has to leave the diagonal and travel in the slow lane, because the black king has shouldered him aside. Black gets his king to the danger zone first, the pawn and rook get exchanged and it's a draw.
That's why 71. Rf2 is imperative. White forces black to take a straight route to the danger zone, via the h file, and black doesn't get a chance to shoulder the white king out of the way.
Diagonals are faster than up and across, and if the caped crusader says it's by a factor of 1.4, who am I, his humble ward to disagree? Holy Pythagorean theorem, Batman!
|Jun-25-10|| ||Marmot PFL: There really is not so much for white to try in this position. The most obvious idea is simply to come back with the king ASAP - 71 Kb7 Kf6 72 Kc6 Ke5. Now it is hard for white to progress; 73 Kc5 g4 74 Kc4 Ke4 and white's king is kept back.|
So look at some rook moves - 72 Rf2 to restrict the BK. 72...Kg6 73 Kb7 g4 74 Kc6 Kg5 75 Kd5 g3 (there are alternatives but white's plan is much the same) 76 Rf8 Kg4 77 Ke4 g2 (Kh3 Kf3) 78 Rg8+ Kh3 79 Kf3 and wins. Not terribly hard, but very easy to mess up at the end of a long game when tired and low on time, or if you get overconfident and impatient with the opponent to resign.
|Jun-25-10|| ||muralman: I got this one. I counted out the White King's diagonal march versus the Black King and pawn. The two pieces being moved gave the White King time to intercept. I took the rook to a passive recluse at the eighth rank where it could come swooping down when the Kings bumped heads. I figured that out, because the two Kings would have to leave space for it.|
|Jun-25-10|| ||WhiteRook48: i missed that.|
|Jun-25-10|| ||watwinc: HELP!
I'm running the Chess Viewer Default, and I followed the line down to g1(N), but I can't get the "pawn promotes to ..." to work.
Any ideas, please?
|Jun-25-10|| ||patzer2: <Once>, I liked your analogy of the swiss knife and all its gadgets in alayzing today's Friday, 71. Rf2!, puzzle solution.|
For me, its somewhat analogous to trying to round up a calf on foot for ear tagging, branding etc. Most any rancher or farmer will tell you the way to catch the calf is to round up and keep the Mama cow under control, as the calf will never stray far from its mother. It also helps to have a good cattle dog. Once the cow and calf are cornered or penned, you can often come in from behind and scare the mother away to capture the calf.
In this case, the Black pawn is like the calf and the Black King is like the cow. Round up and get the King under control, and you'll have time to bring your own King into play to join the Rook (like the cattle dog keeping the Mama cow under control until the old slow farmer can close in on the spooked calf) and capture the pawn.
Of course the Rook, like a good cattle dog, has a lot of slick maneuvers and tricks it uses to keep the cow (Black King) under control. Sometimes the dog will approach the cow from the front or approach it from behind, keeping cow and calf (Pawn and King) in position until the farmer (White King) can move in and put his brand or tag (capture) on the calf (Pawn).
With 71. Rf2! the Black King is cut off and must go to the h-file to try and escort the pawn toward promotion. The only problem is that in the final position, when play might to 76...Kh3 77. Kf3, Black can't advance the g-pawn because of the mate threat 77...g2 78. Rh8#.
|Jun-25-10|| ||Patriot: This didn't take me very long to see, since the white king is needed to help stop the pawn. So cutting off the f-file from the black king is logical. After the pawn attacks the rook, Rf2-f8-g8 is needed. I counted the moves just to make sure it would work and it does.|
|Jun-26-10|| ||Jimfromprovidence: This puzzle turns out to be a counting game, except white needs to get the count in his favor by playing 71 Rf2 first. |
There is no necessity for white to play Rf8 (or Rf7) in order to win at any time!
In the text, white plays 75 Rf8. This is a very efficient move, but 75 Rf1 is perfectly fine as well.
click for larger view
|Jun-26-10|| ||Once: <patzer2> I like it! I can see I have some serious competition in the story-telling stuff.|
|Sep-25-12|| ||vinidivici: Wow, this was a puzzle of the day ??
71.Rf2!!!! is a brilliant move.
That prevents black king to shoulder the white king.
And just what we have seen, the white king finally makes his own way to the sole pawn on the board.
But actually black has made his own fate far before that.
60...Rxf3? is a mistake.
60 ...Kf6! if
61.Kc6 then Rxf3
69.hxg5 fxg5 DRAW
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