Gallardo-Gutiérrez, Eva A.Yakubovich, Dmitry V.2023-06-172023-06-1720190021-217210.1007/s11856-018-1815-9https://hdl.handle.net/20.500.14352/13162Avicou, Chalendar and Partington proved in [4] that an (unbounded) operator Af = G.f′ on the classical Hardy space generates a C0 semigroup of composition operators if and only if it generates a quasicontractive semigroup. Here we prove that if such an operator A generates a C0 semigroup, then it is automatically a semigroup of composition operators, so that the condition of quasicontractivity of the semigroup in the cited result is not necessary. Our result applies to a rather general class of Banach spaces of analytic functions in the unit disc. 1.spajournal articlehttps://link.springer.com/journal/11856open access517.98Teoría de operadoresOperator theorySpaces and algebras of analytic functionsC-semigroupsMatemáticas (Matemáticas)12 Matemáticas