Generalizations of the Coincidence Value Property

Abstract

For $f,g:X\longrightarrow X$ continuous and commuting maps of a Hausdorff space, we investigate various conditions on $X$ and on the pair $(f,g)$ which provide existence of a coincidence value. We introduce generalized notions of the coincidence value property and use this added flexibility to determine how various coincidence properties of $X$ are related to group actions on $X$ and to coincidence properties of associated fibre bundles and adjunction spaces. We also present a sheaf theoretical approach to obtaining information concerning coincidence values through construction of an "almost constant" presheaf. In particular, we prove several partial results concerning the special cases where $X$ is either a low dimensional dimensional sphere or the closed unit disk.