Of course it's Black's turn. Everyone knows that Black must not lose the pawn under any circumstances. Therefore, in a study we will see 1.. Kc6 2. Qb5# and no one will object. However, in a game with time pressure, for example, one would still look for opportunities with 1.. Kc5.
So the author of an endgame study has a certain degree of freedom when it comes to Black's moves. But how far does that go?
Let's see another example.
White to move and win.
The mainline I would like to show is this one: 1. Kb4 Rh4+ 2. Kc3 Rh1 3. Qa8+ Kb6 4. Qa2 Kc7 5. Kd3 Rh3+ 6. Ke4 Rh4+ 7. Kf3 Rh6 8. Qa5+ Kb8 9. Qe5+ Ka8 10. Qe8+ Ka7 11. Qe3+ Ka8 12. Qxh6
1-0, which is also highlighted in the diagram.
All white moves are unique winning moves. One could therefore assume that Black gave White quite a bit of trouble. However, relative to what would have been possible, this is hardly the case. Five black moves were helpful and shortened the play from 44 or more to only 12 moves (you can check this with a database
- please start here).
So, why not use the longer mainline? Because it is full of duals and the whole thing does not even come close to be an endgame study!
These were two extremes of helpful play, one clearly legal and the other one beyond doubt defective.
White to play and win.
S.N. Osintsev
1st prize Griva 70 JT 2023.
The Griva 70 JT was a tourney for baby studies (i.e., up to five pieces) and this was the winning study which was composed by a quite experienced an successful composer. This comment was made in the award (translated from Ukrainian):
"The whole game is based on avoiding the fortress with maximum use of space and ends with mate threats. Ingenious!"
See Problemist Ukraine here.
And here is how the mainline starts. 1. Qh8+ Kb7 2. Qh1+ Rc6 3. Ka4 Kb6 4. Qg1+ Kb7 5. Qg2 Kb6 6. Qf2+ Kb7 7. Qf3 Kb6 8. Qe3+ Kb7 9. Qe4 Kb6 10. Qd4+ Ka6 11. Qd5.
The diagram shows that the white queen went twice from one corner to the next and then performed a staircase approximation. That is quite beautiful and all we need is a great finale. This is provided as 11.. Rd6 (11.. Rb6 12. Qa8#) 12. Qa8+ Kb6 13. Qb8+ Kc6 14. Qb5#.
As you can see, 11.. Rb6? would be a bit too helpful, and 13.. Kc6 is the helpful play we know from the very first example.
But I have chosen this example (and there are several others), because I assume that there is something wrong.
This is the position after 11.. Rf6!. Black is avoiding helpmates and can still hope for the fortress. (Another interesting choice would be 11.. Rc1.) In order to win White has to continue with 12. Qa8+ Kb6 13.Qb8+ when Black plays 13.. Kc6.
In the resulting position, White has five winning moves (Q to b5, b4, b3, b2 and b1) of which Qb5+ and Qb3 are probably best, because they start different lines, both taking 10 more moves of both sides until the rook is won or the pawn has to be moved, while the three other moves prolongue the play even further.
All this was ignored by the author, the judge and presumably also by the audience, because I have not seen an update of the award.
Is this an oversight? Or is this still legal helpful play? Please let me know your opinion.
I cannot add a guestbook here, but you can use this one.
PS: I could not find the Griva 70 JT at Chess Study Art. If the tournament becomes available there, the question should rather be discussed there.