# Thread: Problem on lexicographic order

1. ## Problem on lexicographic order

Hello!

How to find well ordered sets $(X,<_1), (Y,<_2)$ such that $X\times Y$ with lexicographic order isn't isomorphic to $Y\times X$ with lexicographic order?

Thank you!

2. ## Re: Problem on lexicographic order

See why ordinal multiplication is not commutative.

3. ## Re: Problem on lexicographic order

Originally Posted by emakarov
See why ordinal multiplication is not commutative.

Makarov, thank you very much for this information.