OWR-12732-005 · Complete auxiliary counterexample

A Three-Vertex Counterexample to Product-Order Lifting of TF Classes

Manuscript 26 October 2026 · Online 26 October 2026

math.RTmath.COUnrefereed preprint

Abstract

Does every comparison in the facial semistable order admit coordinatewise ordered representatives in the corresponding TF-equivalence classes? We give a complete counterexample for the path algebra of 3 -> 2 -> 1. The classes C = {(-a,-b,a+b): a,b > 0} and D = {(-c,0,c): c > 0} satisfy a cover relation C < D, but no point of C is coordinatewise comparable with any point of D. Both classes lie on the hyperplane perpendicular to (1,1,1). We compute the strict and weak semistable torsion classes directly from the six interval modules and prove that even the transitive closure of the representative relation misses this cover. This answers the auxiliary lifting question in Hanson, A facial order for torsion classes, Remark 4.19. It does not resolve OWR-12732-005 or the general conjecture that g-vector cones determine the support tau-tilting order. The English manuscript includes an explicit proof, scope statement, source attribution and reproducible exact-arithmetic diagnostics. It is an unrefereed preprint with no claim of formal verification or absolute priority.

Record

Affiliation
Mercury Software GmbH
Result
Complete auxiliary counterexample
Categories
math.RT · math.CO
Manuscript
26 October 2026
Online release
26 October 2026
Version
1.0
License
Creative Commons Attribution 4.0 International

Files and verification

The PDF is the canonical reading copy. The source archive contains the LaTeX manuscript, bibliography, reproducibility material, and audit documents without build artefacts.

Citation

Alper Ferudun, “A Three-Vertex Counterexample to Product-Order Lifting of TF Classes,” EulerSolve Research Papers, OWR-12732-005, 2026. https://doi.org/10.5281/zenodo.23672459.

BibTeX
@misc{ferudun2026tflifting,
  author = {Ferudun, Alper},
  title = {A Three-Vertex Counterexample to Product-Order Lifting of TF Classes},
  year = {2026},
  howpublished = {EulerSolve Research Papers},
  url = {https://eulersolve.org/papers/owr-12732-005/},
  doi = {10.5281/zenodo.23672459},
  note = {OWR-12732-005; unrefereed preprint}
}

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