Is it genuinely possible for white to checkmate black in this position?

"is it permissible to play out a bishop-versus-knight endgame"

• Yes, always.

"Does it not fall under point 1.5?"

• No, a series of legal moves exists to checkmate from both sides.

"what about a queen-versus-bishop endgame"

• A series of legal moves exists for the queen to checkmate the bishop's side, but no series of legal moves exists for the bishop to checkmate the queen's side.

@tpr said ^

"is it permissible to play out a bishop-versus-knight endgame"

• Yes, always.

"Does it not fall under point 1.5?"

• No, a series of legal moves exists to checkmate from both sides.

"what about a queen-versus-bishop endgame"

• A series of legal moves exists for the queen to checkmate the bishop's side, but no series of legal moves exists for the bishop to checkmate the queen's side.

<Yes, always.>
<No>

Are these two answers to a question about playing out a bishop-versus-knight endgame?

Both sides can win:
N vs. N, B vs. N, B vs. P, N vs. P, R vs. N, B vs. B (opposite color), Q vs. R
One side can win:
R vs. B, Q vs. B, Q vs. N
No side can win:
B vs. B (same color)

@tpr said ^

Both sides can win:
N vs. N, B vs. N, B vs. P, N vs. P, R vs. N, B vs. B (opposite color), Q vs. R
One side can win:
R vs. B, Q vs. B, Q vs. N
No side can win:
B vs. B (same color)

<It is up to the arbiter to judge if 11.1 was violated or not.
Classical time control, plenty of time left, last round of a tournament, the grandmaster loses against his untitled opponent, who scores a master norm.>

<"is it permissible to play out a bishop-versus-knight endgame"

Yes, always.>

Always or by the arbiter's decision?

"is it permissible to play out a bishop-versus-knight endgame"

• Yes, always, the arbiter has no role to play.

yes it is permissible to try to win if theoretically possible. I've seen such games end in result (rook vs rook) as the other player just tired and blunders. Of course the master level player do not do it.

In sudden-death ending there would possibility for arbiter to intervene that player is not trying to win by normal means - if the other player request game to be drawn. That does not apply to blitz if I remember correctly..

" that player is not trying to win by normal means"

• Such a rule is no longer in place as far as I know.
  I remember a player once requested a draw against Korchnoi and the arbiter was to honor that claim, but Korchnoi was furious and said: you both are to stupid to understand that I am trying to win by normal means.

The rule is still in play for quickplay finish without increment.
III.1 A ‘quickplay finish’ is the phase of a game when all the remaining moves must be completed in a finite time.

III.2.1 The Guidelines below concerning the final period of the game including Quickplay Finishes, shall only be used at an event if their use has been announced beforehand.

III.2.2 These Guidelines shall apply only to standard chess and rapid chess games without increment and not to blitz games.

III.3.1 If both flags have fallen and it is impossible to establish which flag fell first then:

III.3.1.1 the game shall continue if this occurs in any period of the game except the last period.

III.3.1.2 the game is drawn if this occurs in the period of a game in which all remaining moves must be completed.

III.4 If the player having the move has less than two minutes left on his/her clock, he/she may request that an increment extra five seconds be introduced for both players. This constitutes the offer of a draw. If the offer refused, and the arbiter agrees to the request, the clocks shall then be set with the extra time; the opponent shall be awarded two extra minutes and the game shall continue.

III.5 If Article III.4 does not apply and the player having the move has less than two minutes left on his/her clock, he/she may claim a draw before his/her flag falls (see also Article 6.12.2). He/She shall summon the arbiter and may pause the chessclock. He/She may claim on the basis that his/her opponent cannot win by normal means, and/or that his/her opponent has been making no effort to win by normal means:

III.5.1 If the arbiter agrees that the opponent cannot win by normal means, or that the opponent has been making no effort to win the game by normal means, he/she shall declare the game drawn. Otherwise he/she shall postpone his/her decision or reject the claim.

III.5.2 If the arbiter postpones his/her decision, the opponent may be awarded two extra minutes and the game shall continue, if possible, in the presence of an arbiter. The arbiter shall declare the final result later in the game or as soon as possible after the flag of either player has fallen. He/She shall declare the game drawn if he/she agrees that the opponent of the player whose flag has fallen cannot win by normal means, or that he/she was not making sufficient attempts to win by normal means.

III.5.3 If the arbiter has rejected the claim, the opponent shall be awarded two extra minutes.

III.6 The following shall apply when the competition is not supervised by an arbiter:

III.6.1 A player may claim a draw when he/she has less than two minutes left on his/her clock and before his/her flag falls. This concludes the game. He/She may claim on the basis:

III.6.1.1 that his/her opponent cannot win by normal means, and/or

III.6.1.2 that his/her opponent has been making no effort to win by normal means. In III.6.1.1 the player must write down the final position and his/her opponent must verify it. In III.6.1.2 the player must write down the final position and submit an up-to-date scoresheet. The opponent shall verify both the scoresheet and the final position.

III.6.2 The claim shall be referred to the designated arbiter.

One word. time

@petri999 said ^

yes it is permissible to try to win if theoretically possible. I've seen such games end in result (rook vs rook) as the other player just tired and blunders. Of course the master level player do not do it.

In sudden-death ending there would possibility for arbiter to intervene that player is not trying to win by normal means - if the other player request game to be drawn. That does not apply t...

It is important not to confuse a "rook versus rook" endgame with a "knight versus bishop" endgame. This is because the loss of a rook leads to a forced checkmate, whereas in a "bishop versus knight" endgame, only a cooperative checkmate is possible.

@tpr said ^

"is it permissible to play out a bishop-versus-knight endgame"

• Yes, always, the arbiter has no role to play.

You’ve concluded that the arbiter has no influence. Does that mean the bishop-versus-knight endgame falls under point 1.5 after all?