2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/67106This paper deals with a question of Fontaine and Rapoport which was posed in math.NT/0204293. There they asked for the determination of the index set of the Harder-Narasimhan vectors of the filtered isocrystals with fixed Newton- and Hodge vector. The aim of this paper is to give an answer to their question.16 pages, LaTeXNumber TheoryAlgebraic Geometry14D25 (Primary) 14L05 (Secondary)text