  We give a simple algebraic description of opetopes in terms of chain
complexes, and we show how this description is related to combinatorial
descriptions in terms of treelike structures. More generally, we show that the
chain complexes associated to higher categories generate graphlike structures.
The algebraic description gives a relationship between the opetopic approach
and other approaches to higher category theory. It also gives an easy way to
calculate the sources and targets of opetopes.
