The powers of unmixed bipartite edge ideals.

Banerjee, Arindam; Mukundan, Vivek

In this paper, we study the depth and the Castelnuovo–Mumford regularity of the powers of edge ideals which are unmixed and whose underlying graphs are bipartite. In particular, we prove that the depth of the powers of the edge ideal stabilizes when the exponent is the same as half the number of vertices in the underlying connected bipartite graph. We also define the idea of "drop" in the sequence of depth of powers of ideals. Further, we show that the sequence of depth of the powers of such edge ideals may have any number of "drops". In the process of proving these results we put forward some interesting examples and some questions for future research. As for regularity, we establish a formula for the regularity of the powers of such edge ideals in terms of the regularity of the edge ideal itself.

BIPARTITE graphs; EDGES (Geometry)

Journal of Algebra & Its Applications, 2019, Vol 18, Issue 11, pN.PAG

0219-4988

Academic Journal

10.1142/S0219498819502098