nicow wrote:

Thank you Kozibrada! I almost began to think no-one had interest in this new kind of puzzle!

And you would be right if the cage {F7,G7} is 5-. Then the puzzle indeed is incorrect.

With -5 it has only one solution!

I’m sorry, I thought “−5” cage, of course.

I noticed something else, and it could be a useful tip for potential no-op (and not only for “negative”!

) puzzles. Your one contains only 2-cell cages, so it would mean in practice (

**if we omit the rule about forbidden negative result at subtraction**) that |−n−| = |n−|… e.g. |−2 − (+2)| = |+2 − (−2)| = 4. But it same doesn’t always apply to “more”-cell cages.

I’ve chosen 3-cell L-shape in 3×3 no-op calcudoku with [−1, 0, 1]. In the sketch, except valid combinations, the last combination shows a possible result +1−, not −1−. So here |−n−| ≠ |n−|…