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tjaalzchess 19 ( +1 | -1 )
Mate with only knight and bisschop?? The endgame is me with only a knight and bishop.

My opponent offers a draw, saying I cant mate her. But is it really impossible to mate someone with bishop, knight and king?

chessnovice 6 ( +1 | -1 )
... We can't really talk about ongoing, active games.
ganstaman 41 ( +1 | -1 )
Right, we can't offer help in these situations, but printed or online material (not tablebases) can. Check out any endgame book, or something like wikipedia. That will legally help you play the ending.

Just for starters, there should be a useful link somewhere on here:
ionadowman 49 ( +1 | -1 )
Without looking at the position... ... I think it is reasonable to make a general response to the question.

Yes: a K+B+N can, in general, force mate against a lone K. But the technique isn't easy. In your game (assuming you are already in such an endgame), you have 50 moves to effect the mate from the last pawn move or capture (there are no more pawns to move, and any further capture will instantly reduce the game to a draw through lack of material). Else, it is a draw. I don't think one can say more at this point...
ccmcacollister 5 ( +1 | -1 )
hmmm He didn't say what Color that Bishop was . . . }8-D
marinvukusic 45 ( +1 | -1 )
... That is probably the most difficult practical ending in chess (I am not counting studies obviously).

In Blitz:
- I couldn't deliver that mate against a significantly weaker player
- One IM couldn't mate me
- I watched a FM fail to deliver the mate

I am confident I could do it in correspondence chess without any help but it is objectively not to be expected from a player of your rating. That does not mean you can't learn how to do it before you end the game.

Use of tablebases is forbidden.
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tjaalzchess 16 ( +1 | -1 )
Thanks for the response.

I wasn't asking for help, but just a simple yes or no ( possible or impossible ), because I had never seen a endgame with knight and bishop.
8ballphoenix 79 ( +1 | -1 )
Somewhere Amongst the annotated games a few months ago someone (I can't remember who) posted a few complicated endgame studies, one of which was a K+N+B vs K endgame. Obviously this wouldn't help with the game in question as it only studies from one position, with one sequence of moves, but it does explain the general technique.

Is there any way of searching the annotated games for a particular game?

I've not yet been in a position where I have to achieve this mate, though I have been close a few times. Should it happen I'm not sure I could see it through but it would be interesting to try and I too wouldn't accept a draw offer. I certainly wouldn't expect my opponent to resign though.

Incidentally I have played the person mentioned several times and in her defence have always found her to be a polite and pleasant opponent.
ionadowman 88 ( +1 | -1 )
Bragging time! I've had B+N+K vs lone K 3 times in the past - and won them all.

I ought to leave it at that, but I have to confess that I've been lucky on all three occasions for the pieces already to be very favourably placed so that the mate was achieved in maybe a dozen or so moves. It helped, too, that I knew what the forced mate position should look like.

It also has to be admitted that all 3 were pick-up games - not a single tournament game among them. The only time I saw such an ending in a tournament game was at the universities' Arts Festival in Auckland, 1972. Both were strong players (I'll call them Roger and Craig), but Craig was expected to win. Instead Roger attacked from the gun, Craig had to defend the whole game and finally baled out into this ending. And Roger could not win it. Not in 50 moves. Draw.

Altogether and interesting endgame.
lighttotheright 62 ( +1 | -1 )
That is interesting...a draw between two strong players in this endgame! It's possible.

I know this BN vs. K endgame like the back of my hand. I used to study it all the time before I moved onto the more difficult endgames. I don't even have to think while playing it and can beat anyone or any computer in 32 moves or less from any position. It is easy for me.

Although this particular endgame is rare, studying it is valuable because you learn the relationship between the knight and bishop. This translates into better play in the middle game. Also openings tend to be less timid.
marinvukusic 90 ( +1 | -1 )
Interesting quote from Wikipedia "Although this is classified as one of the four "basic checkmates" (the others being king and queen; king and rook; or king and two bishops against a lone king), it only occurs in practice approximately once in every 5000 games (Müller & Lamprecht 2001)."

Sounds about right. This is the precise reason many strong players have problems with it in time trouble (and obviously time trouble is common in OTB chess). Everybody learns it at some point in time but after a few years of never even seeing it the player forgets (and does not refresh his memory practicing a technique that is viewed as unlikely to ever be needed).

The method is not 100% intuitive and there is a pretty small margin of error - 33 moves are needed to deliver chackmate in worst case scenarion, and every slip can easily extend the process beyond 50 moves.
lighttotheright 96 ( +1 | -1 )
Although every book I've seen on the subject says 33 moves, I've proved to my satisfaction that it can be done in 32 or less. Again, the technique to reduce the endgame by the one move seems counter-intuitive at first (but with a deeper analysis it actually makes perfect sense).

Most tutorials on the subject only tell you that you need to drive the King to the edge and then to a corner. The detailed explanations only come with driving the King from the wrong corner into the correct corner and then delivering mate. Most leave it up to the student to figure out how to drive the King out of the center of the board.

If you drive the King out of the center in the proper way, then your King does not need to travel as much to create the necessary opposition to 'force the hand of the defender'. You save at least a move in the worse scenario and are much less likely to make a mistake because the technique is clearer (at least in my mind).
tjaalzchess 25 ( +1 | -1 )
Resigned to bad my opponent resigned

I was going to checkmate her :


The next steps would be :

96. Kh7 Kf7
97. Kh6 Bh4
98. Kh7 Bg5
99. Kh8 Ng6+
100. Kh7 Nf8+
101. Kh8 Bf6#

( mate in 18 moves from last capture)

tim_b 6 ( +1 | -1 )
Nice one! The title of the tournament is appropriate - it wasn't a draw and you proved it.
ionadowman 64 ( +1 | -1 )
I think I can guess... ... why your opponent got so toey: she threw away a fine chance to bring the thing to a quick draw. Here's the plot, with white about to play her 40th move:
White played 40.h4!!
Now, after Black's reply, it is possible she thought she had blundered...
But White's next was the mistake...
41.Kf5?? ...
White had an instant draw with 41.Kd5!, and after the bishop moves, 42.Rh8 ... 43.Rxf8+. Protecting the bishop don't help (41...Nd7 42.Rxd7), nor does taking the rook (41...Nxh7 42.Kxc5). Black had no way to avert the loss of one of the minor pieces, so it's an easy draw. Almost study-like...
tjaalzchess 20 ( +1 | -1 )
Yes I also saw that mistake.Before that point I would have been happy with a draw, so I was prepared for a bishop - rook exchange. Things turned out different.

ionadowman 34 ( +1 | -1 )
Incidentally... ... If you want to see R+2P vs B+N, check out sago vs ionadowman. Sorry - can't give the link; the game was played nearly a year ago now...
bonsai 22 ( +1 | -1 )
32 moves - counter example Regarding lighttotheright's comment:"Although every book I've seen on the subject says 33 moves, I've proved to my satisfaction that it can be done in 32 or less. "

No, a counter example is white to move (mate in 33):
white: Ka1, Bc1, Nb1
black: Kc2
heinzkat 13 ( +1 | -1 )
lighttotheright 18 ( +1 | -1 )
bonsai--That is a good find, but...

When is that position ever going to turn up in a game?

It's a little bit like expecting to be able to mate in the wrong corner, isn't it?
tag1153 13 ( +1 | -1 )
My first on GK
ionadowman 37 ( +1 | -1 )
tag1153... Not bad! Decisively finished, too.
A belated thanks to heinzkat, too, for providing the link to my game vs sago. I still haven't finished annotating the thing...
buddie 22 ( +1 | -1 )
K, B + N Mate Here I am on the wrong end of the K,B + N mate.

By the way, anyone played a game on GK longer than 130 moves?
ccmcacollister 55 ( +1 | -1 )
buddie ... I don't know about other games, but one here on GK was over 3000 moves. Obviously they were trying to make it as long as possible. IMO 130 is quite long for a "real" game.
* * * * * * *
I've only had one of mine, maybe two, go that long in my 30+ years of playing otb tournaments. And the one I recall was an endgame of R vs R+N with no pawns, vs a Master, and took over 8 hours to play! Naturally, I was on the weak side of that ending, but did manage to Draw when we both got so tired an important move was overlooked which made it impossible to be won within the "50 Move Rule".
loreta 3 ( +1 | -1 )
K + B + N vs K all depends on a color of chessboard ....