[Python-ideas] Implement __add__ for set and frozenset
jh at improva.dk
Tue Jun 3 21:43:09 CEST 2008
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.
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