TomaLexi: @posetcay: I tested it with 3 different Katago models and none suggested that move to be significantly worse. Here is AI sensei as an example with 10.000 readouts: https://bit.ly/4gcdST9
As AI is prone to changing its opinion after finding another 10.000 or even 100.000 readouts, I dont think its fair to call M15 a bad move by any means.
caranthir: According to my Katago, R9 is also playable, about the same as M15. If we accept M15, then R9 should be ok too. I don't know what's the best policy; to accept the absolute best in some cases or to always have a variety of correct options. (A traditional Japanese pro way of teaching would be to require not only the move, but a rationale behind it; teaching this kind of stuff would make much more sense in a live setting rather than a plain multiple choice). Anyway, even here, the bottom line is that the player gets some feedback even if the move is not formally "accepted" in the problem, as is the case with M15 - the message says it's fine- fine on the order of -0.1 to -0.2 points. That is of course practically meaningless, and there's much more importance in the fact whether or not you get to play the kind of game that you like or understand better than the opponent.
TomaLexi: C and A are both -0.1 moves for black. C is a very strong move, as it is also sente against whites group on the side. They should both be correct.
posetcay: KaTrain considers N4 to be significantly better.
According to my Katago, R9 is also playable, about the same as M15. If we accept M15, then R9 should be ok too. I don't know what's the best policy; to accept the absolute best in some cases or to always have a variety of correct options. (A traditional Japanese pro way of teaching would be to require not only the move, but a rationale behind it; teaching this kind of stuff would make much more sense in a live setting rather than a plain multiple choice). Anyway, even here, the bottom line is that the player gets some feedback even if the move is not formally "accepted" in the problem, as is the case with M15 - the message says it's fine- fine on the order of -0.1 to -0.2 points. That is of course practically meaningless, and there's much more importance in the fact whether or not you get to play the kind of game that you like or understand better than the opponent.