Zero set

In mathematics, and more specifically in geometry and topology, the zero set of a real-valued function f : X → R (or more generally, a function taking values in some additive group) is the subset of X (the inverse image of {0}). In other words, the zero set of the function f is the subset of X on which . The cozero set of f is the complement of the zero set of f (i.e., the subset of X on which f is nonzero).