A Universal Approach to Vertex Algebras

We characterize vertex algebras (in a suitable sense) as algebras over a certain graded co-operad. We also discuss some examples and categorical implications of this characterization.Comment: To appear in the Journal of Algebr

On Sabidussi-Fawcett subdirect representation

AbstractSabidussi's representation theorem for symmetric graphs is generalized to fairly general concrete categories. As applications, the lists of the irreducible objects in several cases (for instance, symmetric or directed graphs with or without loops, n-partite graphs, posets) are presented

Dualities and dual pairs in Heyting algebras

We extract the abstract core of finite homomorphism dualities using the techniques of Heyting algebras and (combinatorial) categories.Comment: 17 pages; v2: minor correction