English

Maximal Digraphs With Respect to Primitive Positive Constructibility

Combinatorics 2022-10-11 v2 Rings and Algebras

Abstract

We study the class of all finite directed graphs up to primitive positive constructability. The resulting order has a unique greatest element, namely the graph P1P_1 with one vertex and no edges. The graph P1P_1 has a unique greatest lower bound, namely the graph P2P_2 with two vertices and one directed edge. Our main result is a complete description of the greatest lower bounds of P2P_2; we call these graphs submaximal. We show that every graph that is not equivalent to P1P_1 and P2P_2 is below one of the submaximal graphs.

Keywords

Cite

@article{arxiv.2103.08625,
  title  = {Maximal Digraphs With Respect to Primitive Positive Constructibility},
  author = {Florian Starke and Manuel Bodirsky},
  journal= {arXiv preprint arXiv:2103.08625},
  year   = {2022}
}
R2 v1 2026-06-24T00:11:52.046Z