The split exactness conjecture for matching-complex deletion sequences

Let n3n\geq3, let ee be an edge of the complete graph on nn vertices, and let Mne\mathsf{M}_n\setminus e be the matching complex with the vertex ee deleted. Consider the sequence

0H~d(Mne;Z)H~d(Mn;Z)eH~d1(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 n3n\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.

Sources & referencesView supporting material

Primary source

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

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