SMS scnews item created by Bill Unger at Thu 18 Sep 2025 1612
Type: Seminar
Distribution: World
Expiry: 25 Sep 2025
Calendar1: 25 Sep 2025 1500-1600
CalLoc1: SMRI Seminar Rm
CalTitle1: Coefficients of modular polynomials
Auth: billu@bizet.maths.usyd.edu.au

Computational Algebra Seminar: Breuer -- Coefficients of modular polynomials

Speaker: Florian Breuer (Newcastle)
Title: Coefficients of modular polynomials
Time & Place: 15:00 - 16:00, Thursday 25 September, SMRI Seminar Room
Abstract: 
For every positive integer N there is a modular polynomial $\Phi_N(X,Y)$ with integer
coefficients which vanishes precisely at pairs $(j_1, j_2)$ of j-invariants of elliptic 
curves linked by a cyclic isogeny of degree N. These polynomials play an important role 
in cryptography and algorithmic number theory. 

I will give a student-friendly introduction to these polynomials and review what is 
known about the (rapid!) growth of their coefficients. Finally, I will present some new 
results showing that these coefficients are highly divisible by small primes.


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