English

Rigid Graph Products

Operator Algebras 2026-05-13 v4 Functional Analysis

Abstract

We prove rigidity properties for von Neumann algebraic graph products. We introduce the notion of rigid graphs and define a class of II1_1-factors named CRigid\mathcal{C}_{\rm Rigid}. For von Neumann algebras in this class we show a unique rigid graph product decomposition. In particular, we obtain unique prime factorization results and unique free product decomposition results for new classes of von Neumann algebras. Furthermore, we show that for many graph products of II1_1-factors, including the hyperfinite II1_1-factor, we can, up to a constant 2, retrieve the radius of the graph from the graph product. We also prove several technical results concerning relative amenability and embeddings of (quasi)-normalizers in graph products. Furthermore, we give sufficient conditions for a graph product to be nuclear and characterize strong solidity, primeness and free-indecomposability for graph products.

Keywords

Cite

@article{arxiv.2408.06171,
  title  = {Rigid Graph Products},
  author = {Matthijs Borst and Martijn Caspers and Enli Chen},
  journal= {arXiv preprint arXiv:2408.06171},
  year   = {2026}
}

Comments

Added a new result (Theorem F) and shortened section 5.1, stated results for infinite graphs where possible. To appear in Analysis & PDE

R2 v1 2026-06-28T18:10:28.761Z