King+Bishop vs King+Knight NOT forced draw

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20th July 2008, 10:12am
#1
by tamagen
London United Kingdom
Member Since: Mar 2008
Member Points: 67

Several people thought a king+bishop vs king+knight should be an automatic draw (myself included); but it's not:


20th July 2008, 10:18am
#2
by jhuschstp
St. Paul United States
Member Since: May 2008
Member Points: 234

I don't get it...I don't see the mate...what's the point?


20th July 2008, 10:26am
#3
by sstteevveenn
Wales United Kingdom
Member Since: Dec 2007
Member Points: 1634

It is a forced draw, but just like a forced win, you dont necessarily have to force it. 


20th July 2008, 10:27am
#4
by cuendillar
Stockholm Sweden
Member Since: Jan 2008
Member Points: 823

The other way around is possible too, but it takes just as much cooperation.


20th July 2008, 10:28am
#5
by tamagen
London United Kingdom
Member Since: Mar 2008
Member Points: 67

Yes, white would have to be crazy to play Nh7, but the point is that King+Bishop is enough to technically mate against King+Knight, and that this material distribution is therefore not an automatic draw (unlike King+Bishop vs King).

Come to think of it, King+Knight can also mate against King+Knight in much the same way:

 


20th July 2008, 09:25pm
#6
by marl-shie
Manila Philippines
Member Since: Oct 2007
Member Points: 163

I think it is a rule of self-mate puzzle. I tried several times to solve this kind of puzzle in a three-mover moves. However, sometimes I did not succeed to solve the puzzle. Thanks for this kind of idea. I appreciate your puzzle. God bless!


20th July 2008, 09:44pm
#7
by likesforests
United States
Member Since: May 2007
Member Points: 4407

mandelshtam> These formal rules always give me a headache , and i would like to know what the manual says, and if it does.

In the United States, both players would likely agree to a draw. If that didn't happen, after 50 moves it would be ruled a draw. If one of them flagged, it would be a draw by insufficient material to win on time. If one of them helped the other checkmate them... well, then it's checkmate. I can't help you with the rules in Germany.


20th July 2008, 09:54pm
#8
by NM ozzie_c_cobblepot
United States
Member Since: Feb 2008
Member Points: 3839
*sigh*
20th July 2008, 10:29pm
#9
by udin_jelek
kampung Indonesia
Member Since: Apr 2008
Member Points: 3

 it can happend, if king on corner right?


20th July 2008, 10:56pm
#10
by NinjaBear
Salt Lake City (USA) China
Member Since: Oct 2007
Member Points: 720

I guess it's the same - for bishops

(btw this is my first puzzle post! xD I'll probably do it all wrong

)

 

Same goes for the cooperation ^^


20th July 2008, 11:26pm
#11
by zlhflans
Tampa Bay, Fl United States
Member Since: May 2008
Member Points: 2768

i would probably lose some how


21st July 2008, 01:10am
#12
by tamagen
London United Kingdom
Member Since: Mar 2008
Member Points: 67

I should just clarify - this wasn't meant to be a "puzzle"; it was just a demonstration that those pieces do not imply an immediate and automatic draw.

I mistakenly used the word "forced" instead of "automatic" in my original post, so this may have caused some confusion.

If one player does not stupidly allow the other to mate him in this way, then it will *become* an automatic draw only after the 50 move rule takes effect (i.e. 50 moves after the last capture or pawn move). So if you're playing a blitz game in this position, er - make your 50 moves quicker than your opponent, or you will lose on time.

 


21st July 2008, 08:19am
#13
by sstteevveenn
Wales United Kingdom
Member Since: Dec 2007
Member Points: 1634

would that really be a draw in the usa if someone flagged?  With Fide rules it would be a loss if you flagged, because with the worst moves you would lose. 


21st July 2008, 08:30am
#14
by likesforests
United States
Member Since: May 2007
Member Points: 4407

I'm looking at USCF 14E right now, which states you cannot lose on time (even with a delay clock) if your opponent has only:

  • King
  • King & Bishop (and no forced win)
  • King & Knight (and no forced win)
  • King & Two Knights (and no forced win, and you have no pawns)

Presumably because, your opponent would never win these endings on the board. The series of moves required (above) is pretty contrived.


21st July 2008, 08:38am
#15
by sstteevveenn
Wales United Kingdom
Member Since: Dec 2007
Member Points: 1634

yeah, makes sense.  I think Fide should add that to their rules, which afaik currently assume worst play even in such ridiculous situations. 


21st July 2008, 08:53am
#16
by mueller
United States
Member Since: Feb 2008
Member Points: 239

I can mate on 2nd move as black. Does that mean I have a forced mate? no.

Just because it is possible does not mean it will ever happen in real life. Although admittedly, 2nd move mate is probably more likely than either of those scenarios you've shown with K+N v K+B etc.

I don't know what you mean by automatic. Nothing in chess is automatic. All those charts you're showing are called helpmates rather than anything that people would play otb.


21st July 2008, 10:29am
#17
by tamagen
London United Kingdom
Member Since: Mar 2008
Member Points: 67

mueller wrote:

I don't know what you mean by automatic. Nothing in chess is automatic. All those charts you're showing are called helpmates rather than anything that people would play otb.


I don't know how I can explain it any more clearly. Lord knows, I've had enough attempts at it. Maybe nobody really reads an entire message. Who knows?

In chess, a game is automatically over when a king is checkmated.

In chess, a game is automatically drawn when a king is stalemated.

In chess, a game is automatically drawn if the only pieces left are insufficient for checkmate. The four such possible scenarios are:

  1. King vs King, or
  2. King vs King & Bishop, or
  3. King Vs King & Knight, or
  4. King & Bishop vs King & Bishop if and only if both bishops are on the same coloured squares.

In chess, believe it or not, a game is automatically drawn if one player has only a King and the other player runs out of time on the clock.

Got that? Good. Next:

A game is not automatically drawn after a position is repeated three times. One player must claim the draw, and the other is not permitted to refuse it. Nevertheless, the draw claim must be made if a draw is wanted.

A game is not automatically drawn if the last 50 moves made by each side result in no piece capture or pawn movement. One player must claim the draw, and the other is again not permitted to refuse it.

Ok. Have you worked out what's coming next? I imagine not, but it was the original point of the post:

A game is not automatically drawn, nor may a draw be claimed, if the only pieces left are:

  1. King & Knight vs King & Bishop, or
  2. King & Knight vs King & Knight, or
  3. King & Bishop vs King & Bishop if and only if the bishops are on differently coloured squares.

Players in this situation can obviously offer and agree upon a draw should they so wish, but are under no obligation to do so.

This is for FIDE; likesforests pointed out that USCF would require you to demonstrate a forced win to an arbiter should you wish to avoid a draw under USCF rules.

Everyone pointing out the obvious fact that an opponent would have to be pretty stupid to cooperate, or - wait for it - these would be helpmates(!) are astonishing in their capacity to utterly miss the point. This is a post about the player's need to understand when they can formally and implicitly invoke the rules of draws, or when they would need to explicitly claim a draw, and when a draw is neither automatic nor claimed, but merely agreed upon. It was not supposed to be a half-witted opportunity to render trivial, non-sensical puzzles in the hope of eliciting comments of corresponding quality. Sigh^2.


21st July 2008, 10:55am
#18
by fischeryouth
Autorive France
Member Since: Apr 2008
Member Points: 173

just a thought, wouldn't someone have to be a complete idiot if they where to co-operate in the way white did in the first post?


21st July 2008, 11:17am
#19
by jhuschstp
St. Paul United States
Member Since: May 2008
Member Points: 234

yes, they would, but as dude made very clear a post or so back, that's not the point.


22nd July 2008, 06:29pm
#20
by Marshal_Dillon
New Jersey United States
Member Since: Apr 2008
Member Points: 447

Try getting your opponent into any of the demonstrated positions before 50 moves or three-fold repetition occurs. The mates are not forced. Either side can play a move other than the one that blocks his king into the corner. A tournament director would call a draw if summoned to a board with king-knight vs king-bishop. 


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