The set documentation [http://docs.python.org/3.4/library/stdtypes.html] states

"The subset and equality comparisons do not generalize to a complete ordering function. For example, any two disjoint sets are not equal and are not subsets of each other..."

Could "complete ordering" be changed to "total ordering"? This is the correct mathematical terminology. A total ordering is one where every pair is comparable. A complete ordering is one where each bounded subset has a supremum/infimum (for example, reals form a complete ordered field). This can be verified at Wikipedia [http://en.wikipedia.org/wiki/Total_order] and essentially every set theory book.