Dry Ten Martini conjecture for type-I operators

From papers

Let α\alpha be irrational and let vCω(T,R)v\in C^\omega(\mathbb{T},\mathbb{R}). Write Σv,α\Sigma_{v,\alpha} for the spectrum and Nv,αN_{v,\alpha} for the integrated density of states. An energy EkΣv,αE_k\in\Sigma_{v,\alpha} is type-I when its T-acceleration satisfies ω(Ek)=1\overline{\omega}(E_k)=1. Dry Ten Martini conjecture. For any irrational α\alpha and any vCω(T,R)v\in C^\omega(\mathbb{T},\mathbb{R}), each type-I energy EkΣv,αE_k\in\Sigma_{v,\alpha} satisfying

Nv,α(Ek)kα(modZ)N_{v,\alpha}(E_k)\equiv k\alpha\pmod{\mathbb{Z}}

is a boundary of an open gap. This is a type-I form of the Dry Ten Martini Problem, asserting that every gap allowed by the gap-labeling condition is open in this regime. A complete characterization of the spectral gaps remains open.

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Primary source

Xianzhe Li, Disheng Xu and Qi Zhou, “Monotonicity, global symplectification and the stability of Dry Ten Martini Problem”, arXiv:2601.02222 (2026).

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