2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/132418We show that for every Dugundji compact $K$ of weight aleph one the Banach space $C(K)$ is 1-Plichko and the space $P(K)$ of probability measures on $K$ is Valdivia compact. Combining this result with the existence of a non-Valdivia compact group, we answer a question of Kalenda.8 pages; correctedFunctional AnalysisGeneral TopologyPrimary: 46B26; Secondary: 46E15, 54C35, 54D30text