Latin Squares with Few Transversals

Abstract

Let $t(n)$ denote the minimum number of transversals in a Latin square of odd order $n$. Improving upon a recent bound of Dai, Divoux and Kelly, we prove that for every $n$ such that $n \equiv 3 \pmod 6$, \[ t(n) \leq \left( \left(1+o(1)\right) \frac{2n}{3e^2}\right)^n . \] Our proof is based on a family of $3 \times 3$ block Latin squares whose transversals are constrained to either lie entirely in the diagonal blocks or avoid them altogether.