An identity involving 3-regular graphs
The author shows that if \(M\) is a perfect matching in a 3-regular graph \(G\), then the number of positive-minus-negative \(M\)-covers of \(G\) is equal to the number of positive-minus-negative \(M\)-partitions of \(G\). Also, either there are no \(M\)-partitions of \(G\), or every \(M\)-partition and every \(M\)-cover has the same sign.
scientific article; zbMATH DE number 897584