2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/173751Here a new condition for the geometry of Banach spaces is introduced and the operator--valued Fourier multiplier theorems in weighted Besov spaces are obtained. Particularly, connections between the geometry of Banach spaces and Hormander-Mikhlin conditions are established. As an application of main results the regularity properties of degenerate elliptic differential operator equations are investigated.16Functional AnalysisClassical Analysis and ODEs34G10, 35J25, 35J70text