My Bongard problem n.16. Easy, I think. I should mix topics more. Try to write your solution (with a spoiler if you want), and to spot any mistakes of mine. I'll give my solution to this problem under a spoiler in a day or two.

For more info about Bongard problems in general take a look at my first messages:
https://mathstodon.xyz/@leonardom/116110015131667314
https://mathstodon.xyz/@leonardom/116110093951382315

#bongardproblem #mathpuzzle #puzzle #visualmath