Spectral Theory
Eigenvalue bounds for the hyperbolic Laplacian, spectral gaps, and arithmetic quotients.
The eigenvalue conjecture proposes that the first non-zero eigenvalue of the hyperbolic Laplacian on congruence quotients satisfies λ₁ ≥ 1/4.
// Selberg's 1/4 conjecture for congruence Γ ⊂ SL(2,ℤ): λ₁(Δ on L²(Γ\ℍ)) ≥ 1/4
Atle Selberg's conjecture sits at the intersection of spectral geometry, automorphic representation theory, trace formulas, and the theory of expanders. It remains a central open problem, despite substantial progress on explicit lower bounds for many families.
Eigenvalue bounds for the hyperbolic Laplacian, spectral gaps, and arithmetic quotients.
Maass forms, representations of GL(2), and links to Ramanujan-type bounds.
Expanders, the Alon–Boppana bound, and automorphic constructions of optimal spectra.
The Selberg trace formula and the relationship between geodesics and eigenvalues.
Symmetric powers, GL(n), and the broader Langlands framework.
Counting closed geodesics and improving error terms in the prime geodesic theorem.