On the number of error correcting codes

Series
Combinatorics Seminar
Time
Friday, October 11, 2024 - 3:15pm for 1 hour (actually 50 minutes)
Location
Skiles 005
Speaker
Nitya Mani – MIT – nmani@mit.eduhttps://www.mit.edu/~nmani/
Organizer
Xiaoyu He

We show that for a fixed $q$, the number of $q$-ary $t$-error correcting codes of length $n$ is at most $2^{(1 + o(1)) H_q(n,t)}$ for all $t \leq (1 - q^{-1})n - 2\sqrt{n \log n}$, where $H_q(n, t) = q^n / V_q(n,t)$ is the Hamming bound and $V_q(n,t)$ is the cardinality of the radius $t$ Hamming ball. This proves a conjecture of Balogh, Treglown, and Wagner and makes progress towards a 2005 question of Sapozhenko.