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Cantor measures with odd base do not admit Fourier frames

Jaume de Dios Pont, Lukas Liehr, Mitchell A. Taylor

math.FA Jul 9, 2026 · v1
The main theorem that odd-base Cantor measures admit no Fourier frame is formalized and verified in Lean 4 using Mathlib.
We prove that the Cantor measure with base $b$ does not admit a Fourier frame whenever $b > 1$ is an odd integer. In particular, this answers a question of Strichartz on the existence of a Fourier frame for the middle third Cantor measure. A formalization of our main result in Lean 4 is also provided.

It is unknown whether certain Cantor measures, such as the middle-third Cantor measure, admit a Fourier frame, a question of Strichartz. Frame-spectrality generalizes the existence of an orthonormal Fourier basis.

The authors prove that the Cantor measure with base b does not admit a Fourier frame for any odd integer b>1. The argument uses Haar functions on Cantor sets, self-similarity of the measure, and a contradiction argument based on estimates of the Fourier transform modulus. The main result is additionally formalized in Lean 4, relying on Mathlib's measure-theoretic definitions, with the theorem statement curated by the authors and proof files partly generated by large language models.

The Cantor measure with odd base b admits no Fourier frame, answering Strichartz's question for the middle-third Cantor measure. The main theorem was Lean-verified via the statement NoFourierFrameExists.