Khalil Besrour

activity

20192025

collaborators

4 papers

math.NT2025

Jacobi pole divisors and supersingular lifts

Khalil Besrour, Hicham Saber, Abdellah Sebbar

We study the reducible parameter values of a second-order modular differential equation for the full modular group and show that their pole data is controlled by a single polynomia…

math.NT2024

On level 2 Modular differential equations

Khalil Besrour, Abdellah Sebbar

In this paper, we explore the modular differential equation $y^{''} + F (z) y = 0$ on the upper half-plane $H$ , where $F$ is a weight 4 modular form for $Γ_{0} (2)$ .…

math.NT2024

Hypergeometric solutions to Schwarzian equations

Khalil Besrour, Abdellah Sebbar

In this paper we study the modular differential equation $y^{''} + s E_{4} y = 0$ where $E_{4}$ is the weight 4 Eisenstein series and $s = π^{2} r^{2}$ with $r = n / m$ being a rational number in red…

math.NT2019

Modular groups and planar maps

Abdellah Sebbar, Khalil Besrour

In this paper we give an explicit formula for the number of subgroups of the modular group of a given index that are genus zero and torsion-free and a formula for their conjugacy c…