Compute Frobenius homomorphisms on higher-rank web basis elements

Compute the Frobenius homomorphism on web basis elements for higher-rank quantum groups, particularly for ranks de3, to clarify its expected connections with canonical bases, positivity properties, and categorified structures.

Background

The paper studies the PGL_2 skein theory at roots of unity and computes the Frobenius homomorphism explicitly for web bases on the 3-punctured sphere and the closed torus. It places these results in the broader context of higher-rank skein algebras, where determining the Frobenius map on webs is expected to illuminate canonical-basis phenomena and related categorified structures.

The unresolved problem concerns quantum groups of rank higher than two, in contrast to the explicit PGL_2 computations carried out in the paper. The statement is presented as an important open problem rather than as a question resolved by the paper.

References

For higher rank quantum groups, it is an important open problem to compute the Frobenius homomorphism on web basis elements due to the expected connection to canonical bases which exhibit positivity properties and are related to categorified structures .

— $\rm{PGL}_2$ webs at roots of unity  (2610.01881 - Higgins et al., 1 Oct 2026) in Section 1, Introduction