collaborators

7 papers

math.CO2026

A coarse block-cutvertex tree-decomposition

Sandra Albrechtsen, Agelos Georgakopoulos

We obtain a coarse version of the block-cutvertex tree-decomposition of a connected graph.

math.CO2026

A coarse Menger theorem for hyperbolic graphs, finitely presented groups, and more

Sandra Albrechtsen

Menger's theorem is one of the most fundamental results in graph theory. It states that if a graph does not contain disjoint paths between two given sets and of ver…

math.CO2026

A coarse Halin Grid Theorem with applications to quasi-transitive, locally finite graphs

Sandra Albrechtsen, Matthias Hamann

We prove a coarse version of Halin's Grid Theorem: Every one-ended, locally finite graph that contains the disjoint union of infinitely many rays as an asymptotic minor also contai…

math.CO2026

Counterexample to the conjectured coarse grid theorem

Sandra Albrechtsen, James Davies

We show that for every there exists a graph that does not contain the -grid as a -fat minor and is not -quasi-isometric to a g…

math.CO2026

Small counterexamples to the fat minor conjecture

Sandra Albrechtsen, Marc Distel, Agelos Georgakopoulos

We narrow the gap between the family of graphs that do and the family of graphs that do not satisfy the fat minor conjecture by obtaining much simpler counterexamples than were pre…

math.CO2025

Asymptotic half-grid and full-grid minors

Sandra Albrechtsen, Matthias Hamann

We prove that every locally finite, quasi-transitive graph with a thick end whose cycle space is generated by cycles of bounded length contains the full-grid as an asymptotic minor…