A(x, y) = (x2+y2)112 and 7r(x, y) =x. Suppose Fis a subset of a disk D and / is a mapping of T into [O, l]; we are concerned here with conditions under which / can be extended to a mapping of D onto [0, l] which is topologically equivalent to A or to it. Recall that a mapping u: A->B is topologically equivalent to a mapping w: A'-tB' if there exist homeomorphisms h: A->A' and k: B-*B' such that
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.