2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/91775In this communication, we consider the normal ordering of sums of elements of the form (a*^r a a*^s), where a* and a are boson creation and annihilation operators. We discuss the integration of the associated one-parameter groups and their combinatorial by-products. In particular, we show how these groups can be realized as groups of substitutions with prefunctions.15 pages, 23 references. Presented at the Third International Workshop on Contemporary Problems in Mathematical Physics (COPROMAPH3), Porto-Novo (Benin), November 2003Quantum PhysicsCombinatoricstext