2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/78797Some formulae are given for the enumeration of certain types of dissections of the convex (n+2)-gon by non-crossing diagonals. The classical Schroeder and Motzkin numbers are addressed using a cataloguing tool, the "reversive symbol". The elementary details are referred to three Web addresses.2 pagesCombinatoricsNumber Theory05A15; 11B83text