The implementation contains an infinite loop that is broken when a quantity is less than or equal to 1, however the loop never ends on the following input:

sage: g=graphs.PetersenGraph()
sage: g.fractional_chromatic_index(solver="GLPK")

The problem seems to depend on the LP solver, using PPL seems to work just fine. Issue seems to be GLPK and CBC/Coin.

Relevant sage-devel thread at 1.

Relevant ask.sagemath thread at 2.

Component: graph theory

Keywords: graph-theory

Author: David Coudert

Branch: ceb0eb8

Reviewer: Dima Pasechnik

Issue created by migration from https://trac.sagemath.org/ticket/23658