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Published online by Cambridge University Press: 18 May 2009
Let A be a closed subset of a topological space X and f a continuous mapping of A into X with the following two properties:
1.1. f {Fr (A)} & f {Int (A)} are disjoint.
1.2. The mapping f* = f | Fr (A) is 1–1.
It is proved in [5], that if X is the euclidean n–sphere Sn = {x; x e Rn+1 and ― x ― = 1}, then
1.3. f {Fr(A)} = Fr {f(A)}.
[ Hence f{Int (A)} = Int {f(A)}].