Abstract: | Abstract We show that every θ-proximity as defined by V.V. Fedor?uk is an f-proximity which we call a k-proximity. Two related f-proximities are introduced, viz. t- and d-proximities. The smallest and largest members of Mf(X, c) for f=k, d and t are characterised where Mf(X, c) is the family of f-proximities compatible with a given closure space (X, c). |