I was thinking about Oekaki puzzles last night. I was trying to decide if it was possible to design one with multiple solutions.
I figured out it was fairly easy to design some puzzles that multiple solutions that were reflections of each other, but I wasn’t able to figure out any that had more than one non-reflective solution. Is it possible?
Oh yes, I also quickly realized it was easy to figure out simple oekakis that had numerous solutions like puzzles with 1-1-1-1-1 horizontal and vertical series.
You’ve surely found trivial examples, like a 2x2 grid with 1 on each row and column. Now take any more complicated picture, and stick one of those in isolated from any of the other filled-in areas. Presto, your more complicated picture also now has multiple solutions. There are also some more complicated ambiguities, where you can’t tell something like
o o
oXXXXXoo
X X
X X
ooXXXXXo
o o
from
o o
ooXXXXXo
X X
X X
oXXXXXoo
o o
where the Xs are filled in, the os are empty, and all the other squares could be anything at all. I even once saw one in GAMES magazine which had two possible solutions, this way (though from the picture, it was clear which one was “correct”).