Free n-dinilpotent doppelsemigroups

A doppelalgebra is an algebra defined on a vector space with two binary linear associative operations. Doppelalgebras play a prominent role in algebraic K-theory. In this paper we consider doppelsemigroups, that is, sets with two binary associative operations satisfying the axioms of a doppelalgebra. We construct a freen-dinilpotent doppelsemigroup and study separately freen-dinilpotentdoppelsemigroups of rank 1. Moreover,we characterize the least n-dinilpotent congruence on a free doppelsemigroup, establish that the semigroups of the freen-dinilpotentdoppelsemigroup are isomorphic and the automorphism group of the freen-dinilpotent doppelsemigroup is isomorphic to the symmetric group. We also give different examples of doppelsemigroups andprove that a system of axioms of a doppelsemigroup is independent.