2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/119194Suppose G is a second countable, locally compact, Hausdorff, principal groupoid with a fixed left Haar system. We define a notion of integrability for groupoids, and show G is integrable if and only if the groupoid C*-algebra C*(G) has bounded trace.Operator Algebras46L06, 46L055text