2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/114199The toric ideals of $3\times 3$ transportation polytopes $T$ are quadratically generated. The only exception is the Birkhoff polytope $B_3$. If $T$ is not a multiple of $B_3$, these ideals even have squarefree quadratic initial ideals. This class contains all smooth $3 \times 3$ transportation polytopes.11 pagesCombinatoricsCommutative AlgebraAlgebraic Geometry52B20; 14M25; 13P10text