K+R v K+B, K+R v K+N

saemal

Hi.  Just two quick questions: 

1)  Is king and rook versus king and bishop always a forced win from any position?

2)  Is king and rook versus king and knight always a forced win from any position?

I've seen a few of these endgames, in which the side with the rook won, but I'm not so sure it's a solved win from any position.

Silfir

That would be two very quick "No" answers, since the questions do not exclude positions in which the weaker side can immediately win the rook, even with the rook side to move if the rook is forked.

Even failing that, I think there are defense techniques that should ensure that there is a forced win in only a small percentage of possible positions. According to Wikipedia, Rook vs. Bishop can be won if the defending king can be forced into a square of the opposite color of the bishop, whereas the endings against a knight are forced wins pretty much only if the knight can be trapped or otherwise won.

Anyway, unless you and your opponent are both master strength, whether the positions involved are theoretically drawn is not the main factor that decides victory.

rooperi
Silfir wrote:

That would be two very quick "No" answers, since the questions do not exclude positions in which the weaker side can immediately win the rook, even with the rook side to move if the rook is forked.

Even failing that, I think there are defense techniques that should ensure that there is a forced win in only a small percentage of possible positions. According to Wikipedia, Rook vs. Bishop can be won if the defending king can be forced into a square of the opposite color of the bishop, whereas the endings against a knight are forced wins pretty much only if the knight can be trapped or otherwise won.

Anyway, unless you and your opponent are both master strength, whether the positions involved are theoretically drawn is not the main factor that decides victory.


Well, Wikipedia has it wrong here. The opposite colour corner is exactly where tha defending King should seek safety.

wasdQwerty

I know 100% Sure that K+R vs K+B is not 100% win from any position. For example

Silfir
rooperi wrote:
Silfir wrote:

That would be two very quick "No" answers, since the questions do not exclude positions in which the weaker side can immediately win the rook, even with the rook side to move if the rook is forked.

Even failing that, I think there are defense techniques that should ensure that there is a forced win in only a small percentage of possible positions. According to Wikipedia, Rook vs. Bishop can be won if the defending king can be forced into a square of the opposite color of the bishop, whereas the endings against a knight are forced wins pretty much only if the knight can be trapped or otherwise won.

Anyway, unless you and your opponent are both master strength, whether the positions involved are theoretically drawn is not the main factor that decides victory.


Well, Wikipedia has it wrong here. The opposite colour corner is exactly where tha defending King should seek safety.


Heh. It honors me that you would presume that this is a case of Wikipedia being wrong rather than me being an idiot. Wikipedia got it right, I just wrote the wrong thing down. Which is kind of a horrid mistake to make. I occasionally confuse left with right and east with west too.

rooperi

Laughing

TomBarrister

Both endings are generally draws with correct play.

robertfisner

bit.ly/ebFWUN

bit.ly/fvUT6f

bit.ly/idv03f

zschess
No,No
NimzoRoy

In practical terms few of these positions are a win because even if there is a win available because the odds of anyone knowing the correct technique are slim. Of course, maybe some draws turn into wins because the defender (the chump with the minor piece) doesn't know the correct drawing technique.

Pick up a used copy of GM Fine's classic Basic Chess Endings to learn about these and all other, well, basic chess endings.

In the meantime you could practice these endings vs a super chess engine such as Houdini, Rybka, Stockfish or Firebird. Most "state-of-the-art" chess engines now play endings with 5 (6?) or less total pieces on the board perfectly. 

Mastermind_95

The answer in that there isnt any forced win... It is 100% draw if both sides play correctly... Take an example of Q vs R endgame ... It is so hard to win it if R plays all best moves ... 

But R vs B is draw although R vs N can be won

Regards

Mastermind_95

Look how long it took me to mate a Chess software Q vs R

Mastermind_95

Since a player with rook has only 50 moves to mate (if not its draw - 50 moves rule) its an immediate draw :) no nned to play it when its draw and it same with night.

fuzzychin

A gracious offer of draw is always appreciated but a time crunch may dictate whether to force your opponent to prove they know how to draw efficiently; in theoretical draws, wins are still be possible if mistakes are made. Rules available to the defender such as "claiming a draw by insufficient material" should be understood and made use of if necessary.

AngeloPardi

R vs N : It's a draw, unless the knight is far away from the bishop or the king and knight are near a corner.

R vs B : it's a draw, unless the defender's king is already in the corner of the same colour as his bishop.

Der-Schachspieler

R versus B is very basic endgame, that everyone should know.. Most times it is a draw.

 

From my book, but I must translate myself :-)

The bishop prevents the white king from taking the opposition (on c6). The draw is always easy, with one exception... bla bla bla.