<P> In contrast to the set - theoretic view, the old formulation avoids considering infinite collections, as avoiding the actual infinite was an important philosophical position of earlier mathematicians . </P> <P> Once set theory became the universal basis over which the whole mathematics is built, the term of locus became rather old - fashioned . Nevertheless, the word is still widely used, mainly for a concise formulation, for example: </P> <Ul> <Li> Critical locus, the set of the critical points of a differentiable function . </Li> <Li> Singular locus, the set of the singular points of an algebraic variety . </Li> <Li> Connectedness locus, the subset of the parameter set of a family of rational functions for which the Julia set of the function is connected . </Li> </Ul> <Li> Critical locus, the set of the critical points of a differentiable function . </Li>

Describe the locus of points that are equidistant from a single point