HIGHER KOSZUL DUALITY FOR ASSOCIATIVE ALGEBRAS

We present a unifying framework for the key concepts and results of higher Koszul duality theory for N-homogeneous algebras: the Koszul complex, the candidate for the space of syzygies and the higher operations on the Yoneda algebra. We give a universal description of the Koszul dual algebra under a new algebraic structure. For that we introduce a general notion: Gröbner bases for algebras over non-symmetric operads.

ON THE COMPLEXITY OF DECIDING HOMOMORPHISM-HOMOGENEITY FOR FINITE ALGEBRAS

In 2006, Cameron and Nešetřil introduced the following variant of homogeneity: we say that a structure is homomorphism-homogeneous if every homomorphism between finitely generated substructures of the structure extends to an endomorphism of the structure. In several recent papers homomorphism-homogeneous objects in some well-known classes of algebras have been described (e.g. monounary algebras and lattices), while finite homomorphism-homogeneous groups were described in 1979 under the name of finite quasi-injective groups. In this paper we show that, in general, deciding homomorphism-homogeneity for finite algebras with finitely many fundamental operations and with at least one at least binary fundamental operation is coNP-complete. Therefore, unless P = coNP, there is no feasible characterization of finite homomorphism-homogeneous algebras of this kind.

Rational Homogeneous Algebras

An algebra A is homogeneous if the automorphism group of A acts transitively on the one-dimensional subspaces of A. The existence of homogeneous algebras depends critically on the choice of the scalar field. We examine the case where the scalar field is the rationals. We prove that if A is a rational homogeneous algebra with dimA > 1, then A2 = 0.