The split exactness conjecture for matching-complex deletion sequences

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Let n≥3n\geq3, let ee be an edge of the complete graph on nn vertices, and let Mn∖e\mathsf{M}_n\setminus e be the matching complex with the vertex ee deleted. Consider the sequence

0⟶H~d(Mn∖e;Z)⟶H~d(Mn;Z)⟶⟨e⟩⊗H~d−1(M[n]∖e;Z)⟶0.0\longrightarrow\tilde{H}_d(\mathsf{M}_n\setminus e;\mathbb{Z})\longrightarrow\tilde{H}_d(\mathsf{M}_n;\mathbb{Z})\longrightarrow\langle e\rangle\otimes\tilde{H}_{d-1}(\mathsf{M}_{[n]\setminus e};\mathbb{Z})\longrightarrow0.

Split exactness conjecture. This sequence, obtained by cutting the long exact 00-ee-22 sequence, is split exact for every n≥3n\geq3 and every dd.

If true, the long exact deletion sequence would decompose into short split exact sequences, giving a direct-sum description of the homology groups. The supplied text gives no proof or resolution, so the conjecture remains open.

References

Primary source

Jakob Jonsson, “Exact Sequences for the Homology of the Matching Complex”, arXiv:1203.5641 (2012).

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