Thank you honeybadger, you are right.
In puzzle 3789, 4. ... 14-19 and 14-20 are both winning. But I played 14-20, it says it's wrong.
Russian puzzel 528...you're forced to make a losing move after which you are a passenger and white executes the shot.
It seems as the position needs to be reversed...i.e. the puzzle player should have the white pieces and find the forcing move and following (nice) shot.
@dg As for Russian puzzle #528, I agree with you.
There is a particular theme in draughts puzzles: countering opponent plans. In #528 black chooses "safe" option which white refutes by a cascade of sacrifices and a shot. If that puzzle was intended for verifying calculation skills, it should be set differently.
In #528 black can equalize by making exchange: e7-d6, f8-e7, and taking backwards h6xf8.
In puzzle 3789 it isn't winning if you play 4. ... 14-20. White can give a king with 47-41 and 30-25 is draw.
@dg and @kalnap
I agree with you. d2-e3 is draw says Aurora Borealis, c1-b2 is losing and the 5th 'best' move. If you change colors, the startingmove c5-d4 is one of the best moves for black, but not the only one. So the puzzle is not good and will be disabled.
The puzzle would be better with the first mistake for white playing c1-b2. And than black executing the shot as shown is this puzzle.
Best of wishes
Russian puzzle #30:
Basically, it is badly composed puzzle.
Of course, it is about breakthrough sacrifice and crowning, but the transformation into shot occurs if black makes ridiculous resistance.
I like the finale of this puzzle, which, indeed, is very spectacular, but I would prefer to give it to anyone for solving only after 5. .. h4xf2.
2822, 4742, 3933 lijkt me ook goed.
En die dan op ander veld natuurlijk ook.
Mistake in puzzle 2236.
18-22 or 8-12 is followed by the 34-30, 24-30 etc is better. Somehow the solutions wants you to sacrifice 2 pieces in the beginning.
For puzzle 4983, starting the combination with 22-18 instead of 21-17 is considered incorrect, but both are easily winning, with 22-18 actually being the computer suggested move.
For frisian puzzle 80, 13-18 45-50 is a winning endgame. (The computer gives #-17)