Title Some rank five geometries related to the Mathieu group M(23) Author Dimitri Leemans Reference J. Combin. Theory Ser. A 95(2001), nr. 2, 365-372. Math. Reviews 2002d:51011 Zentralblatt 0990.51005 Abstract The Mathieu group M(23) is somehow special when we talk about geometries on which it acts flag-transitively because few such geometries are known. In this paper, we construct six rank five geometries on which the Mathieu group M(23) acts flag-transitively and residually weakly primitively (RWPRI).