New lower bounds on tensor rank of $(2,n,m)$ matrix multiplication with GPT-6

RESUMO

The tensor rank of $2\times n$-with-$n\times m$ matrix multiplication is at least $(n+2)m$ if $n\ge 4$ and at least $\left\lceil \frac{24}{5}m \right\rceil$ if $n=3$. Both lower bounds apply over arbitrary fields.