A graphic generalization of arithmetic
  In this paper, we extend the classical arithmetic defined over the set of natural numbers N, to the set of all finite directed connected multigraphs having a pair of distinct distinguished vertices. Specifically, we introduce a model F on the set of such graphs, and provide an interpretation of the language of arithmetic L={0,1,<=,+,x} inside F. The resulting model exhibits the property that the standard model on N embeds in F as a submodel, with the directed path of length n playing the role of the standard integer n. We will compare the theory of the larger structure F with classical arithmetic statements that hold in N. For example, we explore the extent to which F enjoys properties like the associativity and commutativity of + and x, distributivity, cancellation and order laws, and decomposition into irreducibles. 
Bilal Khan, Kiran R. Bhutani, Delaram Kahrobaei