ring

ring x -- yields the ring associated with x.
ring x -- yields the ambient ring of a ring element x.
ring M -- yields the base ring of a module M.
ring C -- yields the base ring of a chain complex C.
ring I -- yields the ambient ring of an ideal I.
ring p -- yields the base ring of a module homomorphism p.
ring f -- yields the base ring of a map of chain complexes f.
ring X -- yields the coordinate ring of an affine variety X.
ring Z -- yields the homogeneous coordinate ring of a projective variety Z.