Consistency of the conditions determining Kollektivs
Arthur H. Copeland · Transactions of the American Mathematical Society · 1937
The expressions pn{K) and p{K) will be used only when the corresponding space S is such that addition and division by a number have a meaning, and p(K) will be used only when the limit exists.f von Mises reserves the term Mischung for the case where the operation is single-valued and its inverse is multi-valued.% de la Vallee Poussin I.