18 Feb
2010
18 Feb
'10
4:28 p.m.
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