While surfing on the London Chess Classic tournament, which will start on December 8th, I tried to solve the problem Yochanan Afek made. It is on that homepage.
Finally I thought I solved the problem and I looked into the solution. I was wrong, FYI.
I looked at the final diagram, which Afek declares draw with the words: Positional draw. Black can choose between perpetual checking and being perpetually checked!
Look at it:
I found this no draw.
I just play
9. ...f1Q -+
10. Ra2+ Ba7+
11. Rxa7+ Kb8
12. Rb7+ Kc8
13. Rc7+ Kd8.
White runs out of checks and black should now win the game.
So I sent my findings to the London Chess Classic pressroom and only a couple of minutes later this was the respons:
Thank you for your feedback. I thought the same thing as you when I first examined the study but the position is definitely a draw. If you take the FEN data for your final position...
3k4/2R5/1K6/8/1P6/8/8/5q2 w - - 0 14
... and visit the Nalimov Tablebase website...
... and input the FEN data where it says "Input FEN", it will confirm that the position is a draw if White continues with b5, Rc6, Rc5 or Rc3. Hard to believe, perhaps, but Black cannot break the fortress of the king, rook and pawn. It wouldn't be a draw if the b-pawn were at b3 - that is why White's 6th move is so important.
Learning every day!