2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/62590We prove the following theorem: Let $π$ be the fundamental group of a finite graph of groups with finitely generated vertex groups $G_v$ having asdim $G_v\le n$ for all vertices $v$. Then asdim$π\le n+1$. This gives the best possible estimate for the asymptotic dimension of an HNN extension and the amalgamated product.12 pagesGroup Theory20H15, 20E34, 20F69text