The Hall algebra group homomorphism conjecture for tau-tilting finite algebras

Let Λ\Lambda be an arbitrary τ\tau-tilting finite algebra. Let G(Λ)G(\Lambda) be the group associated with the relations from 2-simple minded collections, and let H0-PS(Λ)\mathcal{H}_{0\textnormal{-PS}}^*(\Lambda) be the corresponding Hall algebra. The Hall algebra homomorphism conjecture. There is a group homomorphism

ϕΛ:G(Λ)H0-PS(Λ)\phi_\Lambda:G(\Lambda)\longrightarrow\mathcal{H}_{0\textnormal{-PS}}^*(\Lambda)

given on generators by

ϕΛ(XS)=(1[S])1.\phi_\Lambda(X_S)=(1-[S])^{-1}.

The conjecture extends the theorem proved under the assumption that every pair of Hom-orthogonal bricks is either a pair of KK-stones or Ext-orthogonal. The paper verifies the result for polygons corresponding to the Dynkin diagrams B2C2B_2\cong C_2 and G2G_2, while the general case remains open because a classification of all 2-vertex τ\tau-tilting finite algebras is not currently available.

Sources & referencesView supporting material

Primary source

Eric J. Hanson and Kiyoshi Igusa, “Pairwise Compatibility for 2-Simple Minded Collections”, arXiv:1904.03166 (2023).

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