Fig. 2From: Chemical reaction network knowledge graphs: the OntoRXN ontologySchematic depiction of the directed k-representation (above) and the undirected E-representation (below) initially defined in the context of the energy span model and proposed here as building block for OntoRXN. Here, \(\hbox {k}_{{ij}}\) symbols represent rate constants, \(E_{i}\) node energies and \(E_{ij}\), edge energiesBack to article page