English

Limits of action convergent graph sequences with unbounded $(p,q)$-norms

Combinatorics 2022-10-20 v1 Functional Analysis Probability

Abstract

The recently developed notion of action convergence by Backhausz and Szegedy unifies and generalises the dense (graphon) and local-global (graphing) convergences of graph sequences. This is done through viewing graphs as operators and examining their dynamical properties. Suppose (An)n(A_n)_n^\infty is a sequence of operators representing graphs, Cauchy with respect to the action metric. If (An)n(A_n)_n^\infty has uniformly bounded (p,q)(p,q)-norms where (p,q)(p,q) is any pair in [1,)×(1,)[1,\infty)\times(1,\infty), then Backhausz and Szegedy prove that (An)n(A_n)_n^\infty has a limit operator which, moreover, must be self-adjoint and positivity-preserving. In the present work, we construct a large class of graph sequences whose only uniformly bounded (p,q)(p,q)-norm is the (,1)(\infty,1)-norm, but which converge nonetheless. We show that the limit operators in this case are not unique, not self-adjoint, and need not be positivity-preserving. In particular, in the action convergence language, this means that the space of graphops is not compact. By identifying these multiple limits, we also demonstrate that cc-regularity is not invariant under weak equivalence, where cc is the eigenvalue of the identity function, when the identity function is an eigenfunction.

Keywords

Cite

@article{arxiv.2210.10720,
  title  = {Limits of action convergent graph sequences with unbounded $(p,q)$-norms},
  author = {Aranka Hrušková},
  journal= {arXiv preprint arXiv:2210.10720},
  year   = {2022}
}

Comments

29 pages, 4 figures