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Combinatorial proof of the unbalanced coloring ⇒ unbalanced acyclic orientation implication

Provide a combinatorial proof that any graph with an unbalanced edge coloring (no monochromatic cycles or alternating color trails) necessarily admits an unbalanced acyclic orientation.

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Background

The paper extends a characteristic-independent argument showing that an unbalanced coloring implies independence in a certain matroid, which in turn implies existence of an unbalanced acyclic orientation. However, the authors note the lack of a purely combinatorial proof of this implication.

A combinatorial proof would sharpen understanding of the relationship between coloring-based and orientation-based characterizations in rigidity-related matroids, particularly hyperconnectivity and wedge-power contexts.

References

This implies that a graph with an unbalanced coloring has an unbalanced acyclic orientation, but we do not know a combinatorial proof of this fact.

Rigidity matroids and linear algebraic matroids with applications to matrix completion and tensor codes (2405.00778 - Brakensiek et al., 1 May 2024) in Remark after Proposition 4.3 (Characteristic independence section)