Splitter Theorems for 4-Regular Graphs

Let ${\Phi_{k,g}}$ be the class of all k-edge connected 4-regular graphs with girth of at least g. For several choices of k and g, we determine a set ${\mathcal{O}_{k,g}}$ of graph operations, for which, if G and H are graphs in ${\Phi_{k,g}}$ , G ≠ H, and G contains H as an immersion, then some operation in ${\mathcal{O}_{k,g}}$ can be applied to G to result in a smaller graph G′ in ${\Phi_{k,g}}$ such that, on one hand, G′ is immersed in G, and on the other hand, G′ contains H as an immersion.