2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/136602We study structures of derivation modules of Coxeter multiarrangements with quasi-constant multiplicities by using the primitive derivation. As an application, we show that the characteristic polynomial of a Coxeter multiarrangement with quasi-constant multiplicity is combinatorially computable.12 pagesCombinatoricsCommutative Algebra52C35 (Primary); 32S22 (Secondary)text