On 18 Feb 2010, at 22:06, Daniel Fischer wrote:
...missing are
- c(x) contains x
- c(x) is minimal among the sets containing x with y = c(y).
It suffices*) with a lattice L with relation <= (inclusion in the
case
of sets) satifying
i. x <= y implies c(x) <= c(y)
ii. x <= c(x) for all x in L.
iii. c(c(x)) = x.
Typo, iii. c(c(x)) = c(x), of course.
Sure.
If we replace "set" by "lattice element" and "contains" by ">=", the
definitions are equivalent.
Right.
The one you quoted is better, though.
It is a powerful concept. I think of a function closure as what one
gets when adding all an expression binds to, though I'm not sure that
is why it is called a closure.
Hans
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