Characterizations of ultramaximally monotone operators

Abstract: In this paper, we study properties of ultramaximally monotone operators. We characterize the interior and the closure of the range of an ultramaximally monotone operator. We establish the Brezis--Haraux condition in the setting of a general Banach space. Moreover, we show that every ultramaximally monotone operator is of type (NA). We also provide some sufficient conditions for a Banach space to be reflexive by a linear continuous and ultramaximally monotone operator.