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|Jan-27-20|| ||Cheapo by the Dozen: LIke most folks I went with 55 ... a2. Each move is simple and forcing.|
|Jan-27-20|| ||saturn2: It is also lost if white were to move|
|Jan-27-20|| ||Ratt Boy: After 55…a2 56.♔b2 ♗xc4 is also winning, though I guess the game continuation queens more quickly.|
|Jan-27-20|| ||zb2cr: 55. ... Bxc4+ sets White an unsolvable problem. If he moves the King away, his Bishop drops. Black can then easily walk his King over to support Queening the e-Pawn.|
If 56. Bxc4, a2; 57. Kxa2, Kxc4 and the path to Queening the e-Pawn is clear.
|Jan-27-20|| ||TheaN: Perhaps the most interesting here is, what is faster, 55....a2 or Bxc4+?|
The fast SF9 analysis gives 55....Bxc4+ #11, whereas 55....a2 is -132. That is also mate, but it's outside the scope of the ply. This would make 55....Bxc4+ faster. However, there also the practical way of calculating this: the main point is if White doesn't accept the piece trade on c4.
After 55....a2 Black gives away a tempo because White was intending to capture the a-pawn and leave the bishops anyway. After 56.Kxa2 Bxc4+ 57.Kb2! Bxe2 58.Kc3 -+ White blocks d4, meaning that it will a while before Pe3 promotes.
55....Bxc4+ wins a crucial tempo because the a-pawn is captured on a3 instead of a2. After 56.Kxa3 (as said, Bxc4 a2 57.Kxa2 Kxc4 with e2 -+ is just worse) Bxe2 57.Kb2 Kd4: the difference is made, White can't block d4 in time so White can only block d3 with 58.Kc2. However, now 58....Bh5! and White's in zugzwang.
The puzzle itself is not that interesting, as nearly everything wins.
|Jan-27-20|| ||gawain: I found the inferior 55...a2 56 Kb2 Bxc4 Bd1 (or Bf3) 57 Kd4 which wins but allows White to struggle on for a while because it does not get the bishops off the board right away. Should've known this was not the best solution.|
|Jan-27-20|| ||chrisowen: Perjury keyilug keypune keycuey bc4lung conelug keenlug keyilug hubendy rakekey rebudum remater rekeyer keyilug 10 eunichy bc4lung conelug keenlug keyilug dunks it's avidy ableum 56a2 kestrel efforty hudoldy ablerum keyuleg rebudum remater rekeyer keyilug 8 eunichy lurekey perjury gurhitz vastlug piddles donaldkey. |
Withfun factyang keyilug martzit vastlug dipslug keynuby landony footyum keymitz cueendy keyolug keycuey bc4lung conelug keenlug keyilug umsumum flunger citebug keenlug efforty keyilug gilllug lurekey perjury keycuey bc4lung citebug.
|Jan-27-20|| ||jhgrau: nice play!!|
|Jan-27-20|| ||Walter Glattke: a2 is faster for the human player at the board, Bxc4 is faster in moves to set mate for the computers, I like a2 so far.|
|Jan-27-20|| ||chrisowen: Announce it on the day.|
|Jan-27-20|| ||Crowaholic: 55. ..a2, while still winning, is bad play that allows white to greatly delay the mate with 56. Kb2! Bxc4 57. Bf3!|
I don't see any strategy here for Black that doesn't involve promoting the g pawn, which costs a lot of time. Note how, even after trading the e pawn for the white bishop, the black bishop is the wrong color for forcing the promotion of the rook pawn.
There can be a difference between personal preference and objectively inferior moves. The assumption that white will always play 56. Kxa2 with transposition into main line is simply not justified.
|Jan-27-20|| ||DrGridlock: About as tricky as a Monday puzzle gets.
The first line I found (and the one I went with) was the 55 … a2 line. I quickly noticed that after Kxa2 Bxc4+ Bxc4 there was no way for White to stop black's e-pawn. (Computer analysis confirms that this line mates QUICKER than the game continuation of 55 … Bxc4).
The subtlety I missed is that White is not forced to take on a2, and can keep the a pawn from promoting with 56 Kb2. After Bxc4 another subtlety is that White can side-step the bishop with 57 Bh5. Black still has a mate, but it's mate in 20 instead of mate in 13.
It's a Monday puzzle and both continuations work, but over-the-board not finding the 56 Kb2 defense could be costly.
|Jan-27-20|| ||TheaN: <DrGridlock: (Computer analysis confirms that this line mates QUICKER than the game continuation of 55 … Bxc4).>|
What exactly did you use? I'm using SF10 now on the competitor's site and currently on depth 48 it gives Bxc4 #11, a2 #23. This corresponds to the fast analysis of SF9 that couldn't find a forced mate in 55....a2 with depth 39.
The problem with 55....a2 is what I mentioned before. The pawn push in itself does nothing to change the position in Black's favor. It just forces the king to move down.
In fact I erred with 56.Kxa2? (-#13) which still allows 56....Bxc4+ with check. After 56.Kb2! (-#29!) Black is promoting <neither> passed pawn quickly after 56....Bxc4 57.Bg4 Black will first have to bring the king to the e-pawn so the bishop can keep defending a2. If Black goes too fast with 57....e2? 58.Bxe2 Bxe2 59.Kxa2 and about -#23.
55....Bxc4+ (#11) immediately leaves White with either of two evils: trading bishops with an immediate passer, or lose the bishop with the e-pawn still on the board.
|Jan-27-20|| ||Damenlaeuferbauer: After long pondering, my old Ukrainian friend Pavel, whose greatest success was reaching the semi-finals of the world cup 2015 in Baku/Azerbaijan, finally found the "most beautiful" (German GM Karsten Müller) move 55.-,Bxc4+! (55.-,a2! 56.Kxa2,Bxc4+ 57.Bxc4,Kxc4 also wins) 56.Bxc4,a2 57.Kxa2,Kxc4 with the same position as above. By the way, this nice ending was published in Informator 133, page 88.|
|Jan-27-20|| ||DrGridlock: Thea - I used the new Fritz engine.
Yes - a2 mates in 23 against BEST defense.
The quicker mate - that I alluded to in my post - is if White plays 56 Kxa2 after 55 … a2.
The quicker mate (against degraded defense) is what "persuaded" my too-quick solution to the puzzle of 55 … a2.
|Jan-27-20|| ||DrGridlock: <The pawn push in itself does nothing to change the position in Black's favor.>|
Here's one thing the pawn push does:
it moves the king away from covering c4. This allows black's bishop to take on c4 with a check (if the king is on a2), or to force the white bishop off of e2. If the white bishop takes on c4, then White's king does not have enough "spring in his step" to stop both the a and e pawns. If the white bishop backs up (to f3,g4 or h5) then black pushes the e-pawn and forces the white bishop to sacrifice itself to prevent the e-pawn from queening.
|Jan-27-20|| ||RandomVisitor: After 21...Qb7 white is doing ok
click for larger view
<45/61 04:32 +0.23 22.h4> Bc6 23.Re1 Rd8 24.Bc4 Bb5 25.Be2 g6 26.Rd1 Rxd1+ 27.Bxd1 Qd7 28.Bf3 Qd6 29.a4 Bc4 30.Qd1 Kf8 31.Qc1 e5 32.Bxe5 Qxe5 33.Qxc4 Qxb2 34.Qxa6 Bf6 35.Qe2 Qa1+ 36.Kg2 Bd4 37.Qc2 Qe1 38.e5 c4 39.Qe2 Qxe2 40.Bxe2 c3 41.Bd1 Bxe5 42.Kf3 Bc7 43.Ke2 Bb6 44.f4 Ke7 45.Bb3 Ba5 46.Kd3 Kf6 47.Bc2 Bb6 48.Kxc3
Stockfish likes 30.Kg2 and 40.c4
|Jan-27-20|| ||laskereshevsky: I prefere 55...♗xc4+ but 55...♙a2 is fine anyway|
|Jan-27-20|| ||JohnDMaster: I had an endgame with almost this exact pawn structure and same bishops! I won the game pretty much the same way! I even pushed the e pawn and played Bxc4 with a forced trade into a winning ending.|
|Jan-27-20|| ||northernfox: It seems to me that 55 ... a2 is a legitimate solution here. There is no bonus in chess scoring related to number of moves to win.|
|Jan-27-20|| ||TheaN: <northernfox: It seems to me that 55 ... a2 is a legitimate solution here. There is no bonus in chess scoring related to number of moves to win.>|
Normally I agree. In this case, I don't. Besides the longer mate, after 55....a2 56.Kb2! Bxc4 57.Bg4 Black <could> potentially still screw this up: a1 is the wrong color for the bishop, and the h-pawns at the time prevent g7 from becoming a factor.
After 55....Bxc4+ Black ends up keeping the e-pawn as 56.Bxc4 loses immediately on 56....a2. After 56.Kxa3 Bxe2 57.Kb3 Kd4 58.Kc2 Bh5 is a rather easy zugzwang and the e-pawn promotes.
|Jan-27-20|| ||TheaN: Well I guess the definition of 'legitimate solution' is still personal. It uses the same methods and wins, so in that regard it isn't inferior. It just gives White too many options (at least a glimpse of escape) in my opinion.|
|Jan-27-20|| ||Breunor: White starts going wrong around move 42. It looks like the computer doesn’t want the white king to get too far away from the king side pawns. But I do find the computer somewhat unreliable on these kinds of positions.|
|Jan-29-20|| ||jith1207: <
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Jan-27-20 little ernie: jith , I'm not fond of cooks,
unless they do my favorite spinach saag paneer & mango-mint chutney. Shanti>
That sounds good :)
|Jan-29-20|| ||jith1207: <chrisowen: Announce it on the day.>:|
When is the announcement, <Chris Owen>?
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