Topological aspects of edge fusions in 4-graphs

Edge fusion on a regular edge-coloured graph is the following operation: delete an edge e, its parallel edges, and its endpoints, and make a new edge coloured c out of the two c-coloured edges formely adjacent to e, for all possible colours. This paper provides a complete analysis of the effect of edge fusion on bipartite 4-edge-coloured graphs and on the 3-dimensional pseudocomplexes represented by them. © 1991