How good are you at handling the Bishop pair?

In chess it is well known that the Bishop pair is a powerful weapon in the hands of a strong player in all phases of the game(opening, middle and endgame).  In the diagrammed position can you force Black out of his fortress in 6 moves or less?

For 300 years this position was believed to be a draw.  It has been shown to be a forced win for White.   White to play can win the knight or force mate in 45 moves.  So it is well within the "50 move" draw rule which makes it a practical endgame that the serious player wants to master.

Even more important to the serious player is the expert handling of the Bishop pair.  Knowing this basic mate will go a long way to making you an expert at handling the Bishop pair in your games.

I will post the solution after a sufficient number of players have posted theirs.

By the way if you solve it with even one wrong move it makes the win 16 moves longer and violates the "50 move" draw rule.

Hi tonydal,

Yes, you are right the extensions in moves and the positions have to be clearly announced by the organizers before the start of the tournament.  Article 10.12 is the one that deals with the 50 move rule specifically.

http://www.chessvariants.org/fidelaws.html

I have seen games recently where GMs are unable to win Q vs. R endgames and unable to draw R vs. N endgames.  But the important thing is that practicing 2B vs. N endgame hones your skills in handling the Bishop pair and gives you insights into the hidden geometries of the board and unique tempo gaining Bishop moves. Skills and insights that will come in handy during your regular games. 

More specifically the tempo gaining skill of the B vs. N in the "mirror effect" when the Bishop changes diagonals off of the end of the board.  That skill transfers enhancing the number of weapons, you as a player have, in your regular games. 

Thanks for your post.  I know I learned something from it.      

oh so in 1980 they extended the 50-move rule for the troitski ending; then tablebases started spweing out too many long endings so by 1990 or so they reverted to 50-move-rule-with-no-execptions; now they've provided an option for organisers to extend it - the present arrangement sounds sensible to me.

This reminds me - for british and commonwealth people: curious fact: the laws of cricket when I last checked say a. an over has to be at least 4 balls [not counting no balls etc]; b. a boundary has to be at least 4 runs. With options to add to the 'at least'.

So it seems every official cricket match has fine-print agreement agreeing to the rules for a sixer and for mandatory 6-ball overs...

Hi normajeanyates,

Yes, I agree, it is a sensible arrangement.

Regarding endgame tablebases, distilling general principles from a tablebase may be more helpful than a thousand optimal variations.  For example understanding how reciprocal zugzwangs affect the outcome of the position.  What, what's a reciprocal zugzwang???    This another fine point that adds immeasurably to your endgame technique. 

'distilling general principles from a tablebase' - bloodly hard and specialised work! I'd leave that to John Nunn & co who have been doing an excellend job of it for 15+ years now; and just read the results ;)

Perhaps a poor choice of words on my part.  Rephrasing:  Using your common sense and employing one's acquired knowledge through reading publications like John Nunn's, Secrets of Minor Piece Endings will increase your playing strength.  In other words, learning the finer points of handling the Bishop pair in this ending will significantly improve your overall game.

A question for you, do you know what a reciprocal zugzwang is?  Do you know how to employ it in a position to gain an advantage?  I can tell you I didn't, but I do now.  Later in this forum I will give specific examples with diagrams.  

I do :) it has another name also - trebuchet?

One example of the trebuchet theme is the following video:

 http://www.chessvideos.tv/forum/viewtopic.php?f=12&t=2443&sid=a38388491b24f2ce4495aaa2a6e0ad4e

It also involves the technique of triangulation.  However, it is only the normal, one-sided, zugzwang.  Reciprocal zugzwang is two-sided.

I guess, I am saying, I would agree with you, if you were right.

Thanks for your posts, they help shed light on dimly lit corners of our chess knowledge. 

Oh actually it depends on the writer - since the word zugzwang is already used in english, some writers define trebuchet as mutual zugzwang.

Like in general topology: what some poeople call compact is what others call compact housdorff, and what some people call quasicompact is what others call compact. [in each, the first term is the Bourbaki School's usage.]

Or maybe i am muddling terms - zugzwang and mutual zugzwang are clear to me - all i remember is that trebuchet was a related term - I do not use the term myself (I am a chess player not a chess writer!)

The trébuchet is a textbook example of reciprocal zugzwang. In fact, a full point is on the line, so it's also one of the most extreme examples.

In the video, the author (correctly) only refers to the position as a trébuchet after the a-pawn is gone and both kings are lined up as in the diagram above.

ok then my memory is not so bad - it would be dangerous if my chess memory got corrupted even under no clock-pressure :) [I didnt check the video yey - i am thinking about 2 games here, 4 bigchess[16x16] on ficgs and how to plan computer analysis on 2 games in a computer-chess tournament  [also ficgs] - also trying out 1(any) ..Nh3 and 1.Nh3 at 3 0 blitz on fics [inspired by  Bill Wall's latest blog] - desparately need a couple of extra heads to manage all that and still see the video right now!

Thanks likesforests for reassuring that i haven't gone absolutely senile yet ;)

oh so a trebuchet is a 1-0 v 0-1 reciprocal zugzwang :)

I will try one last time to clarify the difference between zugzwang and reciprocal zugzwang(or as you prefer mutual zugzwang) in words, before resorting to a more exacting and rigorous methodology.

In Mr. Nunn's own words, "...In a normal zugzwang, it doesn't matter much who is to move, because the superior side usually has a waiting move with which he can pass if it is his turn to move.  This is not so in a reciprocal zugzwang, which may be defined as a position in which whoever moves first has to weaken his position.  In an ending such as B+P v B, where only one side has winning chances, we may be even more precise.  Assuming that White has the bishop and pawn, a reciprocal zugzwang is a position in which Black to play loses, but White to play can only draw.  In other words, not only is Black in zugzwang if it is his turn to move, but White to play has no waiting move to maintain the zugzwang, so he is also in zugzwang if it is his turn to move...", Secrets of MInor-Piece Endings, John Nunn, Henry Holt and Company,1995, p 6.     

transpositions> "This is not so in a reciprocal zugzwang, which may be defined as a position in which whoever moves first has to weaken his position."

That's why the trébuchet is an extreme example of reciprocal zugzwang. Whomever moves first certainly weakens their position--in fact, they lose outright.

Good point likesforests.  I have adjusted my thinking and improved.  I think I am clear, though, that trebuchet is only an one example of a reciprocal zugzwang and doesn't completely define the term.  The complete definition allows for weakening of the position by the side forced to move yet produces a draw. After all as players seeking to improve we are interested in forcing reciprocal zugzwangs that will force a win in an otherwise drawn position or draw in an otherwise lost position.

nomajeanyates, it wasn't my intent to mislead or confuse you.  That is why these forums are so important.  They help all of us to improve in countless ways. 

Speaking of improving, practicing the basic mate 2B vs. N will improve your handling of the Bishop pair in every phase of your game.  Following is a diagram of a reciprocal zugzwang in the 2B vs. N mate which allows the side with the N to draw, [it cannot be forced, it requires error(s) on White's part]:

Thanks to all of you for your posts.

no worry transpositions, I never though you had bad intentions - perish the thought! :)

I prefer to think of zugzwang and mutual [reciprocal] zugzwang in terms of null moves. Assume for the sake of argument that nullmoves are allowed in chess. Then zugzwang is when for the side to move, null move is the unique best move. Mutual zugzwang is a zugzwang where, after the side to move has made their unique  best move - ie null-move; the side now on move is in zugwang - so their only chance is nullmove too :)

By the way here is the famous mutual stalemate game!

From r.g.c. archives - by Shirish Chinchalkar, posted  from Cornall U. on Fri, Jan 7 1994.

transpositions wrote>  practicing the basic mate 2B vs. N will improve your handling of the Bishop pair in every phase of your game.

I think that's a very good idea - now why didn't that occur to me? [you mean when it is a win; or when the lone-Knighter errs of course..] So, practicing against engines both with and without tablebases .. in the latter case, perhaps,  using a 'legacy' program like psion chess?