On Wed, 7 Apr 2010, yary wrote: > 2010/4/6 Larry Wall <la...@wall.org>: > > Set(Read | Write) # bogus, R|W is really 3 sets, R, W, and RW! > > Set(Read & Write) # okay, can only represent RW > > Set(A | B) doesn't seem so bogus to me, if what you want is the power > set

Hmm, surely a power-set would be written as Set(Set(X,Y,...)) or perhaps more mathematically as 2 ** Set(X,Y,...) -Martin