Faster recognition of quasi-triangulated graphs via decremental simplicial-vertex maintenance

Determine whether Triangle Detection, Simplicial Vertex, and high-dimensional Orthogonal Vectors retain n^{\omega}-time algorithms in the decremental setting relevant to recognizing quasi-triangulated graphs, or whether a fine-grained complexity separation emerges among these problems.

Background

A quasi-triangulated graph can be recognized by repeatedly removing a simplicial or cosimplicial vertex, which leads to a decremental simplicial-vertex subroutine. The paper improves the running time of this subroutine but does not establish an n{\omega}-time algorithm. It explicitly identifies as unresolved whether the relevant problems—Triangle Detection, Simplicial Vertex, and high-dimensional Orthogonal Vectors—share n{\omega}-time complexity or exhibit a meaningful difference.

References

Their fine-grained complexity offers an interesting direction for future study, so we leave both problems open to the community.

— Asteroidal Triples and Friends in (Likely Necessary) Matrix Multiplication Time  (2610.22133 - Nogler et al., 15 Oct 2026) in Introduction, final paragraph before the subparagraph "Recognition of Quasi-Triangulated Graphs and Decremental Simplicial Vertex"