English

Large lower bounds for the betti numbers of graded modules with low regularity

Commutative Algebra 2019-10-29 v2 Algebraic Geometry

Abstract

Suppose that MM is a finitely-generated graded module of codimension c3c\geq 3 over a polynomial ring and that the regularity of MM is at most 2a22a-2 where a2a\geq 2 is the minimal degree of a first syzygy of MM. Then we show that the sum of the betti numbers of MM is at least β0(M)(2c+2c1)\beta_0(M)(2^c + 2^{c-1}). In addition, if c9c \geq 9 then for each 1ic/21\leq i\leq \lceil c/2\rceil, we show βi(M)2β0(M)(ci)\beta_i(M)\geq 2\beta_0(M){c \choose i}.

Keywords

Cite

@article{arxiv.1903.12503,
  title  = {Large lower bounds for the betti numbers of graded modules with low regularity},
  author = {Adam Boocher and Derrick Wigglesworth},
  journal= {arXiv preprint arXiv:1903.12503},
  year   = {2019}
}

Comments

14 pages, 2 figures