“…The best known CASs are probably Mathematica [45,50], Maple [12,16,25,37,51], Derive [20,22,30] (recently discontinued) [52], Reduce [24,26,53], Axiom [17,54] Dynamic Geometry Systems (DGSs) are interactive systems that allow to draw "ruler and compass" geometric constructions using only the mouse, and to deform the construction by dragging and dropping the points that do not depend on previously defined objects. The best-known 2D DGSs are probably Cabri Geometry [59], The Geometer's Sketchpad [60], Cinderella [19,61] and GeoGebra [14,62], although many other exist.…”