2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/75078We investigate the integral cohomology ring and the Chow ring of the classifying space of the complex projective linear group PGL_p, when p is an odd prime. In particular, we determine its additive structure completely, and we reduce the problem of determing its multiplicative structure to a problem in invariant theory.I have corrected several typos, added some references, and slightly expanded the introductionAlgebraic GeometryAlgebraic Topology14C15, 14L30, 20G10, 55R35text