Partition Relations for Ordinal Numbers
E. C. Milner · Canadian Journal of Mathematics · 1969
Capital letters denote sets and the cardinal of A is |A|. Greek letters always denote ordinal numbers and, unless stated otherwise, small latin letters denote non-negative integers. The symbol [A]r is used to denote the set {X: X ⊂ A; |X| = r} of all subsets of A with relements. If A is a simply ordered set with the order relation <, then the order type of A with this ordering is written as tp