English

Resolution and Tor Algebra Structures of Grade 3 Ideals Defining Compressed Rings

Commutative Algebra 2021-05-28 v2

Abstract

Let R=k[x,y,z]R=k[x,y,z] be a standard graded 33-variable polynomial ring, where kk denotes any field. We study grade 33 homogeneous ideals IRI \subseteq R defining compressed rings with socle k(s)k(2s+1)k(-s)^{\ell} \oplus k(-2s+1), where s3s \geq3 and 1\ell \geq 1 are integers. The case for =1\ell =1 was studied in a previous paper by the author; a generically minimal resolution was constructed for all such ideals. More recently, this resolution is generalized in the guise of (iterated) trimming complexes. In this paper, we show that all ideals of the above form are resolved by an iterated trimming complex. Moreover, we apply this machinery to construct ideals II such that R/IR/I is a ring of Tor algebra class G(r)G (r) for some fixed r2r \geq2, and R/IR/I may be chosen to have arbitrarily large type. In particular, this provides a new class of counterexamples to a conjecture of Avramov not already constructed by Christensen, Veliche, and Weyman.

Keywords

Cite

@article{arxiv.2004.06691,
  title  = {Resolution and Tor Algebra Structures of Grade 3 Ideals Defining Compressed Rings},
  author = {Keller VandeBogert},
  journal= {arXiv preprint arXiv:2004.06691},
  year   = {2021}
}

Comments

11 pages, added exposition and references. To appear in Journal of Algebra. arXiv admin note: text overlap with arXiv:1912.06949