Full Idea
Iterative sets do not exhibit a Boolean structure, because the complement of an iterative set is not itself an iterative set.
Gist of Idea
Iterative sets are not Boolean; the complement of an iterative set is not an iterative sets
Source
Stewart Shapiro (Foundations without Foundationalism [1991], 7.1)
Book Reference
Shapiro,Stewart: 'Foundations without Foundationalism' [OUP 1991], p.177