alt Hacker News> If you want only quadrilaterals, and you want most vertices to be a meeting between 4 quadrilaterals, but some places 3 quadrilaterals meet, you can use the Euler characteristic to deduce that there must be 8 of these degenerate vertices.
> If you want only quadrilaterals, and you want most vertices to be a meeting between 4 quadrilaterals, but some places 3 quadrilaterals meet, you can use the Euler characteristic to deduce that there must be 8 of these degenerate vertices.