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

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.

Authors

Publication Details

Journal
Zenodo (CERN European Organization for Nuclear Research)
Published
2026-10-26
DOI
https://doi.org/10.5281/zenodo.23672458
Primary Topic
Algebraic structures and combinatorial models
Type
preprint
Controls
|||
ALL TIME
JAN
FEB
MAR
APR
MAY
JUN
JUL
AUG
SEP
OCT
preprint

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

Alper Ferudun
Zenodo (CERN European Organization for Nuclear Research)
Algebraic structures and combinatorial models
preprint

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

Alper Ferudun
preprint en

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.

Zenodo (CERN European Organization for Nuclear Research)
Algebraic structures and combinatorial models
AI Navigator

Ask Laika to Summarize, Analyze, and Connect papers live on the map.

Summarize Papers & Methodologies

Extract key findings, datasets, and comparative methods across publications.

Benchmark Rankings & Visual Analytics

Rank top research institutions, authors, funders, topics, and journals by Field-Weighted Citation Impact (FWCI) and paper volume with instant charts.

Connect Distant Disciplines

Bridge topological clusters on the map to find hidden collaborative intersections.

Laika access coming soon
A Three-Vertex Counterexample to Product-Order Lifting of TF Classes — Alper Ferudun · Zenodo (CERN European Organization for Nuclear Research) (2026) | TGRS Research Map | TGRS