A Theorem in the Partition Calculus Corrigendum

In order to make (19) correct we define X., S(n) (n<(o) a little more caref lly and replace lines 21-31 on Page 504 by the following : Let n < co and s ppose that we have already chosen elements xi c S (ia+a, then choose sets A,A'cA(' ) s ch that A<A' ; if on the other hand a~a+a, then p t A=A'=A( n ) . In either case it is tr e that if x c A and Ai c A', then there is A2 A 1 s ch that {x}<A2. With this remark in mind, it now follows from (10) that there are xn E A, a strictly increasing map gn:B-B and sets A(n+1) (v c B) s ch that