Structural properties of edge-chromatic critical multigraphs

Guantao Chen, Guangming Jing

Appearing in different format, Gupta\,(1967), Goldberg\,(1973), Andersen\,(1977), and Seymour\,(1979) conjectured that if $G$ is an edge-$k$-critical graph with $k\ge \Delta +1$, then $…