English

Induced matching numbers of finite graphs and edge ideals

Commutative Algebra 2019-02-28 v1 Combinatorics

Abstract

Let GG be a finite simple graph on the vertex set V(G)={x1,,xn}V(G) = \{x_1, \ldots, x_n\} and I(G)K[V(G)]I(G) \subset K[V(G)] its edge ideal, where K[V(G)]K[V(G)] is the polynomial ring in x1,,xnx_1, \ldots, x_n over a field KK with each degxi=1{\rm deg} x_i = 1 and where I(G)I(G) is generated by those squarefree quadratic monomials xixjx_ix_j for which {xi,xj}\{x_i, x_j\} is an edge of GG. In the present paper, given integers 1ar1 \leq a \leq r and s1s \geq 1, the existence of a finite connected simple graph G=G(a,r,d)G = G(a, r, d) with im(G)=a{\rm im}(G) = a, reg(R/I(G))=r{\rm reg}(R/I(G)) = r and deghK[V(G)]/I(G)(λ)=s{\rm deg} h_{K[V(G)]/I(G)} (\lambda) = s, where im(G){\rm im}(G) is the induced matching number of GG and where hK[V(G)]/I(G)(λ)h_{K[V(G)]/I(G)} (\lambda) is the hh-polynomial of K[V(G)]/I(G)K[V(G)]/I(G).

Keywords

Cite

@article{arxiv.1902.10429,
  title  = {Induced matching numbers of finite graphs and edge ideals},
  author = {Takayuki Hibi and Hiroju Kanno and Kazunori Matsuda},
  journal= {arXiv preprint arXiv:1902.10429},
  year   = {2019}
}

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11 pages