Adult cats were trained to discriminate between erect and inverted triangles after simultaneous ablation of cortical areas 17, 18, and most of 19 of both hemispheres. Postoperative training proceeded through a graded series of similar triangle pairs in which the members of each pair were equated for luminous flux.

Motivated by various applications triangulations of surfaces using only acute triangles have been recently studied. Triangles and quadrilaterals can be triangulated with at most 7, respectively 10, acute triangles. Doubly covered triangles can be triangulated with at most 12 acute triangles. In this paper we investigate the acute triangulations of doubly covered convex quadrilaterals, and show ...