Zung's spectral-sequence conjecture relating SFC(ϕ,C)SFC(\phi,\mathcal{C}) and CA(ϕ)CA(\phi)

Let ϕ\phi be the flow under consideration, let G+G_+ be its associated graph, and let SFC(ϕ,C)SFC(\phi,\mathcal{C}) and CA(ϕ)CA(\phi) be the chain complexes described above, where C\mathcal{C} is a chosen collection of closed orbits relative to which ϕ\phi has no perfect fits. A multi-loop is a loop, possibly non-embedded, in G+G_+; a non-embeddedness grading records the non-embeddedness of a multi-loop. Consider a chain complex CΩ(ϕ)C\Omega(\phi) generated by all multi-loops of G+G_+, with differential counting strumming of multi-loops and cobordisms of orbits along transverse surfaces. Decompose this differential according to the two filtrations described below. Zung's conjecture. The differential on CΩ(ϕ)C\Omega(\phi) admits the two stated filtrations: one by non-embeddedness, with components dSFC0d^0_{SFC} and dSFCnd^n_{SFC}, and one by surface type, with components dCA0d^0_{CA} counting strumming, dCA1d^1_{CA} counting Fried pants, and dCAnd^n_{CA} counting other transverse surfaces. The spectral sequence from the first filtration collapses at the E1E_1 page and gives H(SFC(ϕ,C))H_*(SFC(\phi,\mathcal{C})), while the spectral sequence from the second filtration has CA(ϕ)CA(\phi) as its E1E_1 page. The first collapse is expected because non-embedded multi-loops have an even number of resolutions, and the second because dCA0d^0_{CA} cancels all but one multi-loop for each multi-orbit. This conjecture proposes a chain-level reconciliation of the two complexes: the first filtration explains the relation with SFC(ϕ,C)SFC(\phi,\mathcal{C}), and the second explains the relation with CA(ϕ)CA(\phi).

Sources & referencesView supporting material

Primary source

Antonio Alfieri and Chi Cheuk Tsang, “Heegaard Floer theory and pseudo-Anosov flows II: Differential and Fried pants”, arXiv:2506.07163 (2025).

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