Last-modified: 2010-09-28 (火) 15:53:57
Let (X,T) be a topological space. A map γ from T to the power set P(X) of X is called an operation if every G in T is contained in γ(G).
T. Fukutake, On operation-paracompact spaces and products, Univ. u Novom Sadu Zb. Rad. Prirod.-Mat. Fak. Ser. Mat. 24, 2 (1994), 23-29.