[postgis-users] 2d operator commutation

[Владимир Кихтенко]

Hello!

I'm messing with behavior of geometry index operators and can't
understand one thing.
Operators &< (overleft) and &> (overright) are defined in Postgres as
comutative to each other.
However their definitions doesn't seem to commute

a &< b    is the same as    a->xmax <= b->xmax
and
b &> a    is the same as    b->xmin >= a->xmin

Right parts of this seem to be completely unrelated.
Do I misunderstand somthing or it is a bug in the definition?

--
Vladimir Kikhtenko