Jordan isomorphisms of skew incidence rings

Abstract

Let [Formula: see text] be a finite partially ordered set, [Formula: see text] a commutative domain and [Formula: see text] an endomorphism of [Formula: see text]. We define the skew incidence ring [Formula: see text] and we prove that each Jordan isomorphism of [Formula: see text] onto an associative ring [Formula: see text] is a near-sum of a homomorphism and an anti-homomorphism.