报告时间： 2025年9月9日（周二）上午 11:00-12:00

报告地点：国交2号楼315会议室

报告人：Prof. Maria  Loukaki 克里特大学(Crete University）

摘要：Let $p$ be a prime number and $\zeta_p$ a primitive $p$-th root of unity. Chebotarev's theorem states that every square submatrix of the $p \times p$ matrix $(\zeta_p^{ij})_{i,j=0}^{p-1}$ is non-singular.  In this talk we will show that a similar property holds for principal  submatrices of $(\zeta_n^{ij})_{i,j=0}^{n-1}$, when  $n=pr$ is the product of two distinct primes, and $p$ is a large enough prime that has order $r-1$ in $\mathbf{Z}_r^*$. As an application,  an uncertainty principle for cyclic groups of order $n$ is established when $n=pr$ as described above.