👉 The term "equicostate" is a mathematical concept in the field of algebraic topology. It refers to a pair of topological spaces where one space is homeomorphic to the other, but the interiors of their respective homotopy groups are not isomorphic. In other words, two spaces are equicostat if they have homeomorphic fundamental groups and the homology groups of their product are not isomorphic. An example of an equicostate pair is the torus (
