Edge Ideals with Regularity No More than Three
Abstract
We prove that if G is a gap-free and chair-free simple graph, then the regularity of the edge ideal of G is no more than 3. If G is a gap-free and P4-free graph, then it is a chair-free graph; furthermore, the complement of G is chordal, and thus the regularity of G is 2.
Research supported by the Natural Science Foundation of Shanghai (No. 19ZR1424100) and the National Natural Science Foundation of China (No. 11971338).
Communicated by Zhongming Tang