# Bongard Problem #107 (solution)

#### Left: Exactly three plain (simple)
sides.

#### Right: Exactly three non-plain
(complex) sides.

*Back to problem #107*

**Note:** Over the years, many people have
contacted me and told me what they think the solution to this
problem is. Only a very small minority (around 5%) of those who
solved this problem managed to see that the number of complex
sides on the right side is exactly three. People usually stop
upon seeing three plain (simple, straight) sides on the left, and
conclude "not three plain sides on the right". Most of
the aesthetically pleasing Bongard problems, though, contain a
pattern on the right side as well, which is not simply the
negation of the left, but a sort of "dual" solution whenever this makes sense
and is possible. If you decide to design
Bongard problems, remember this, please.