Ubiquity of counterexamples to the Smith-Ward problem
Abstract
The Smith-Ward problem about matrix ranges, posed in the 1980s, was recently resolved in the negative by Marcel Scherer (arXiv:2607.04274) by obtaining a three-dimensional operator system without the lifting property. However, this operator system must be exact. In this paper we show that, for every finitely generated -algebra without the local lifting property (LLP), there exists a three-dimensional operator system without the lifting property (LP), thus generalizing Scherer's result and eliminating the reliance on not being a group. In particular, we prove that whenever is a finite-dimensional operator system without the LP, then contains a -dimensional operator system without the LP for some . In this way, we yield a plethora of counterexamples to the Smith-Ward problem. In particular, unlike Scherer's example, these three-dimensional operator systems fail both the LP and exactness. We also prove the existence of a three-dimensional operator system that detects nuclearity for unital -algebras, strengthening previous work of Kavruk (J. Funct. Anal., volume 269, 2015).
Keywords
Cite
@article{arxiv.2607.11001,
title = {Ubiquity of counterexamples to the Smith-Ward problem},
author = {Samuel J. Harris},
journal= {arXiv preprint arXiv:2607.11001},
year = {2026}
}
Comments
15 pages. Comments welcome!