2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/120736We use vertex operator algebras and intertwining operators to study certain substructures of standard $A_1^{(1)}$--modules, allowing us to conceptually obtain the classical Rogers--Ramanujan recursion. As a consequence we recover Feigin-Stoyanovsky's character formulas for the principal subspaces of the level 1 standard $A_1^{(1)}$--modules.minor changesQuantum AlgebraHigh Energy Physics - TheoryCombinatoricsRepresentation Theorytext