2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/106273A recent characterisation of Fock-adapted contraction operator stochastic cocycles on a Hilbert space, in terms of their associated semigroups, yields a general principle for the construction of such cocycles by approximation of their stochastic generators. This leads to new existence results for quantum stochastic differential equations. We also give necessary and sufficient conditions for a cocycle to satisfy such an equation.20 pages; to appear in Math Proc Cambridge Philos Soc. Minor edits carried outFunctional AnalysisProbability81S25; 47D06text