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| diagram 1. White to move |
2R5/3P1pkp/5bp1/1q2N3/p7/6BP/5PPK/8 w - - 1 1
[solution]
UPDATE
Our system I is not so well developed that we recognize the knight fork direct from the beginning. Nor will we be able to develop our system I to that degree. That is what this blog has proven. But can we reach the same solution by applying simple means? Like simple reasoning and the rules for the initiative?
If there is nothing forcing in this position, then we can never force the end combination. Hence there must some force be applied. When we have found a move or two, our system I may find it easier to kick in and reveal the knight fork.
Let's give it a try.
The first thing that must be recognized, is that the immediate promotion is leading us nowhere. Black must give up his bishop, but it might well turn out that we have to sac a piece back to prevent the black a-pawn from promotion.
Then, what is the target?
Both the king and the queen are too volatile to be a target. The most logical target is the promotion of the d-pawn. I consider promotion as a gain of wood, and not different from capturing a queen. d8 is the target. The bishop will try to sac himself to prevent the promotion. The bishop is partly immobile due to his function. This means that the first try must be to deter the bishop from the diagonal OR to trade him off.
1. Ng4 enhances the immobility from both the bishop and the king.
The logical reaction is 1. ... Be7
It is easy to see that after 2. Be5+ the trade of the bishops cannot be prevented.
The other try is 1. ... Qxd7
With one target in place and an immobile king on the board, our system I has way more chance to recognize the fork from this stepping point.
I remembered this problem, but not the solution. It took me two tries.
ReplyDeleteFirst try, I thought 1.Nc6, followed by 2.Be5, but even then that's a lazy try because, for example 2...BxN+, 3.NxB QxN+, 4.g3 Qd4, 5.d7(Q) Qxf2+ is a perpetual.
On the second try, I finally recognized the pattern and got it right. Once you see the pattern, the rest is easy to calculate. For example, if Black tries to avoid it, then 1.Ng4 Be7, 2.Be5+ f6, 3.Bxf6+ BxB, 4.NxB (protecting the d7 pawn) KxN, 5.d8(Q).
I spotted the rook check early on, and that is possibly due to having seen this problem before, but maybe I also found it the first time I faced this problem, dunno. This is one of those problems not likely to be found in a game, except for where someone is either up on their tactics or very tactically proficient. It would be challenging to find this, where the player is overly nervous in time-pressure.
For me such problems are pretty diffcult. However I found out I know the main motif (idea) and now it is only a matter of fiding some critical (key) moves to make success.
ReplyDeleteAfter I found 1.Ng4! I realized that Black plays 1...Be7 and now it is very hard to break through.
I think a way deeper analysis is required. What I mean is to see (understand) all the key ideas (not variations!), especiallt 3. Bxf6+!! I have the tendency to miss such moves every time.
Update in blue
ReplyDeletePerhaps this is one of those positions which can be "solved" using Martin Weteschnik's approach (Understanding Chess Tactics). The idea is to think in terms of a tactical base and two tactical targets. It does not matter in which order the 3 components are created. It suffices to "see" two of the three potentialities in the given position. He takes considerable time to develop the ideas that the tactical targets can be a Pawn/piece, a square or a tactical device (CCT, fork, double attack, etc.).
ReplyDeleteThe difficulty (IMHO) is in understanding that the d7-Pawn is DIRECTLY protected in the initial position AND that the Black King has "wiggle room", i.e., can move. 1. Ng4 puts the Black King in a "box" with no moves. It is only AFTER visualizing this move that the idea of a fork on f6 begins to come into consciousness. Why did it come up into consciousness? Because it "undefends" the d7-Pawn, allowing the Black Queen to capture it with 1. ... Qxd7. Aha! We now have a tactical base on f6 AND a target on d7 within reach of the tactical base. All that is needed is a second tactical target.
Weteschnik emphasizes that the King is a natural target for creating a second tactical target, because it can be "forced" to move as the result of a check. With the Black King in a "box", it is natural to look for a check - the only one available is 2. Rg8+. The Black King is forced to capture, setting up the second tactical target. After 2. ... Kxg8 3. Nxf6+ Kf8 4. Nxd7+, White is easily winning. The first major variation appears to be good for White, which is an encouraging sign of eventual success!
Naturally, we have to go back to determine if there is a different course of action for Black earlier, perhaps on his first move. So what is available to Black after 1. Ng4?
Retaining the Black Bishop comes immediately to mind, especially after "seeing" the fork on f6, so 1. ... Be7 comes into "view." As previously indicated, the Black Bishop has the Function of preventing the d7-Pawn from queening. Both d7 and d8 are PoPs. The Black Bishop also has an extremely limited range of motion. White has the possibility of bringing another piece to bear against the Black King and the f6 square: the White Bishop. 2. Be5+ f6 [2. ... Bf6 3. d7-d8(Q)] 3. Bxf6+ Bxf6 [3. … Kf7 4. Bxe7 Kxe7 5. d7-d8(Q)+]4. Rg8+ Kxg8 [4. ... Kf7 5. Nxf6 and the Pawn queens next move] and we are back to the idea of the first variation.
GM Valeri Beim refers to this process as finding a "resulting move". One variation is worked out to quiescence, and some move within that variation provides "food for thought" for a different variation.
I think it likely that most of us began with the “obvious” push of the White Pawn to promotion, and promptly figured out that it just loses it - 1. d7-d8(Q) Bxd8. White has the numerical material advantage (R+B+N vs. Q), but Black does have a very mobile Queen and another (potential) Queen in the a4-Pawn. For a tactical problem, that just “feels” WRONG as the solution! The next “solution” is to increase the pressure against the Black King; this can only be done by creating a “box” around it which prevents it from moving. The only available move that creates a “box” is 1. Ng4. IMHO, it is only AFTER we “see” that this is the only way forward with (potential) forcing moves (the sacred initiative!) that we become conscious of the fork potentiality tying f6 to d7 (and eventually to g8).
I also could be full of crap, and rationalizing how I came to the conclusion that 1. Ng4 was the correct first move.
When dealing with System 1, “de tar baby don’ say nuthin’.” (Ref.: Song of the South movie (1946), one of Uncle Remus’ stories about Brer Rabbit)
“Oh, Brer Fox, PLEASE don’ throw me back in dat briar patch!”
Both our approaches bear some similarity with drilling a hole in the wall and writing a cross over it, so the hole is always in the middle of the cross.
ReplyDeleteYet there is some merit in what you say. Paraphrasing, if the targets are obscured, the king is probably one of them.
The point is, why should you abandon the d-pawn when you don't see the fork yet? Which question can prevent trial and error here?
@ Temposchlucker asks: (W)hy should you abandon the d-pawn when you don't see the fork yet?
ReplyDeleteI can think of some possibilities to answer your question. (Please note that this is entirely post hoc rationalization, in order of the thoughts, not necessarily in order of importance.)
(1) Since the PRIMARY Function of the Black Bishop is to prevent the promotion of the d7-Pawn, it is "natural" to seek a way of eliminating it. As a result of its Function, the Black Bishop is somewhat limited in its mobility. The encircling motif (Dr. Lasker) "emphasize(s) the two ideas underlying it: the idea of superior force at a given point [square] and that of immobility [of a target]. WHAT IS IMMOBILE MUST SUFFER VIOLENCE. Ergo, the Black Bishop must be attacked. The "natural" consequence is to ask what force(s) are available (in the shortest time) to attack the Black Bishop. The White Rook cannot accomplish this task. Given the limited mobility of the White Bishop "limited by the White Knight on e5), it also cannot accomplish this. This only leaves the White Knight, and the "natural" square from which to attack the Black Bishop is g4. This is the Robert Coble chess module (System 1 subroutine) at work.
(2) In general, in order to have any chance (and to maintain the "initiative"), White must bring ALL of his pieces into play. Ergo, the White Bishop on g3 is currently limited in scope by the White Knight on e5. Moving the White Knight will "liberate" the White Bishop.
(3) Anything which limits the mobility of the Black King is probably "good" to accomplish. Moving the White Knight establishes a "box" of immobility around the Black King, which invokes the encircling motif again.
I "think" this may be the subconscious considerations that led to considering 1. Ng4 as the first move. Having reached this new position, System 1 is "triggered" to consider the new possibilities available, leading to the glimmer of an idea of a potential fork on f6 based on the tactical base (f6) and TWO tactical targets (Qd7 and Kg8). It helps considerably that Black does not have a lot of good alternatives to trying to either snap off that dangerous d7-Pawn or trying to keep it under observation. However, as Nimzovich so eloquently put it, the passed Pawn is a "criminal" who must be kept under lock and key; he must never be allowed even limited freedom to "roam" toward promotion. Observation is (usually) insufficient to thwart the ambitions of a passed Pawn to advance; this is why a passed Pawn MUST be blockaded (made immobile). (This also is the Robert Coble chess module (System 1 subroutine) at work.)
As previously noted, I'm sorry but all this speculation may be a load of crap. It just may be that you either "see" it or you don't, with no rational (System 2) explanation of WHY either possible or available via introspection.
my idea of a perfect solving of a tactical puzzle:
ReplyDeleteRead position
detect tactical weaknesses
judge weaknesses acording to their relevance
start calculations guided by a thoughtprocess
i blundered at this puzzle too , the missing queen made me think i need to promote.
So i missed the (importance of the ) weakness: weak king, the king is weak because 6 squares around him are under attack. A weak king makes it necessary to look for all!! possible and halfway potential!! checks: Be5? Bh6? Bf8? Rg8? Nh5?...
At the end you have to spot the pattern, or calculate "for ever"
Its a general error of mine that i get easily distracted from the "weak king signal"
Yes, that is the key. How to detect the right targets.
DeleteI look at it this way. It's generally most important to find all of the ideas in the position (what you refer to as "patterns"). Then the ideas have to be somehow stitched together. Calculation is often to verify how or that the idea works. Calculation is verification. Calculation is often useless when one is not finding or spotting the ideas that make any such calculation successful.
ReplyDeleteCalculation to find the ideas is possible, and we also do that to an extent, but that is how computers think more than humans. Either way, the visualizing part of calculation is important. If we only learned to do it _thoroughly_!
I hesitate to include the following “problem”, because I am still learning things about it after over 46 years (!!) studying it! I first saw it in E. A. Znosko-Borovsky’s The Middle Game In Chess, pp. 72-73, in early 1972 or somewhat earlier when I began studying that book. It has been included in several other books over the years since it was played. (See Edward Winter’s Chess Notes link below for those sources.)
ReplyDeleteFEN: 1k1r1b1r/p1p1q3/2p1p3/4Ppp1/4nP2/P2BQ3/1PP3PB/2KR3R b - - 0 1
Black to move
I sent in a “refutation” (I thought) to GM Larry M. Evans for analysis and discussion in his Chess Life and Review column “Larry Evans on Chess”, April 1972. This “fact” is recorded in Edward Winters’ Chess Notes, 15 December 2014 - 8976. ‘One of the finest combinations ever played’. Alas! My “refutation” was disposed of in short order by GM Evans. I was USCF rated 1733 at the time, so I should have been able to “see” the refutation – but I didn’t. I just took another look at it today, and found the refutation quite easily.
Link: 15 December 2014 - 8976. ‘One of the finest combinations ever played’
Znosko-Borovsky comments: “At first sight, no Kt [Knight] combination appears to be possible here for no basis can be discerned on which it could be built up.”
That’s the only “hint” I’m going to give for now.
I’m still learning and “seeing” new things in this position, especially with the help of GM Stockfish. FWIW, GM Stockfish does not think very highly of the combination as played; he considers the position to be equal (-0.08) at the end of the variations given, and gives only one variation leading to a Black advantage after running for 5 days continuously. Everything else leads to an advantage for White.
Good luck if you decide to investigate this position!
As usual, Blogger mucks up the link; sorry about that. Here it is as plain text:
ReplyDeleteLink: http://www.chesshistory.com/winter/winter125.html#8976._One