graph: modular decomposition of a single vertex should be a single tree node #38301
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Documentation preview for this PR (built with commit 420692b; changes) is ready! 🎉 |
dcoudert
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Jul 1, 2024
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The modular decomposition tree computed by Sage for a graph with a single vertex is wrong (tested in Sage from 9.8-10.4.rc0)
Sage returns a tree with a
PRIMEroot with a single child representing the vertex0, but according to the recursive definition of a modular decomposition tree, it should be a single node tree (see Wikipedia for example)This PR fixes this issue. It is an easy fix, as the case of single vertex graphs was treated separately in the
modular_decompositionmethod ofGraph.Two doctests were modified to reflect this changes.
📝 Checklist
⌛ Dependencies