Re: [Python-ideas] Implement __add__ for set and frozenset

Arnaud Delobelle wrote:

Difference is not an associative operation though. E.g.

A - (B - B) = A but (A - B) - B = A - B

Same for symmetric difference (here "^" stands for symmetric difference). E.g.

A ^ (B ^ B) = A but (A ^ B) ^ B = A | B

Actually, symmetric difference *is* associative. The second '=' above is wrong unless B is a subset of A. Regards Jacob