Cardinal Invariants

Some articles on cardinal invariants, cardinal invariant, cardinal, invariant, invariants:

Axioms Of Set Theory - Areas of Study - Cardinal Invariants
... A cardinal invariant is a property of the real line measured by a cardinal number ... For example, a well-studied invariant is the smallest cardinality of a collection of meagre sets of reals whose union is the entire real line ... These are invariants in the sense that any two isomorphic models of set theory must give the same cardinal for each invariant ...

Famous quotes containing the word cardinal:

    What people don’t realize is that intimacy has its conventions as well as ordinary social intercourse. There are three cardinal rules—don’t take somebody else’s boyfriend unless you’ve been specifically invited to do so, don’t take a drink without being asked, and keep a scrupulous accounting in financial matters.
    —W.H. (Wystan Hugh)