Review implementation for Partial Ordering of Vectors
Not much to say about it, good job!


Documentation: explain the mathematical explanation of your partial ordering unless it's really that obvious for your intended readers
Names:

In Python, names starting with uppercase letters are for class names: of course you're free to use your own convention, but this one makes it easy to share code between Python developers
Explicit is better than implicit: less is better than l which could also mean left or leave or whatever.

Style: In Python (see PEP8), we usually don't but spaces before function definitions.
Test cases: always add a test case for degenerate cases, eg. the empty list and lists of different lengths: those are the ones which usually fail.


(And +1 to the comments who should become an answer.)