The dimension-zero–dimension-one commutation conjecture for surface Hall algebras

Let SS be the surface in the preceding setup, let CiC_i be one of the distinguished curves, and let [Yi,(d)][\mathfrak Y_{i,(d)}] and [Zi,][\mathfrak Z_{i,\ell}] denote the corresponding dimension-zero and dimension-one Hall classes, with Z\ell\in\mathbb Z and dNd\in\mathbb N. The dimension-zero–dimension-one commutation conjecture. Without assuming S^Ci(Ti^Ci)\widehat S_{C_i}\simeq(\widehat{T_i}_{C_i}), one still has

[[Yi,(d)],[Zi,]]=(CiCi)[Zi,+d].\left[[\mathfrak Y_{i,(d)}],[\mathfrak Z_{i,\ell}]\right]=(C_i\cdot C_i)[\mathfrak Z_{i,\ell+d}].

The claim extends the preceding commutation relation beyond the formal-neighborhood hypothesis. The supplied text gives no proof or resolution, so its status is open.

Sources & referencesView supporting material

Primary source

Duiliu-Emanuel Diaconescu, Mauro Porta, Francesco Sala, Olivier Schiffmann and Eric Vasserot, “Nilpotent cohomological Hall algebras of surfaces”, arXiv:2502.19445 (2026).

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