On Gnomons
On Inscribed Circumscribed Conics.
On Lenz's problem on the independence of the axioms of affine space
On Moser's Problem of Accommodating Closed Curves in Triangles.
On non-localized oriented angles
On Polyhedra with Transitivity Properties.
On propellers from triangles.
On pythagorean angles
On rainbowness of semiregular polyhedra
We introduce the rainbowness of a polyhedron as the minimum number such that any colouring of vertices of the polyhedron using at least colours involves a face all vertices of which have different colours. We determine the rainbowness of Platonic solids, prisms, antiprisms and ten Archimedean solids. For the remaining three Archimedean solids this parameter is estimated.
On rational Morley triangles
On Schläfli's reduction formula.
On the area discrepancy of triangulations of squares and trapezoids.
On the area of a polygon in the hyperbolic plane.
On the bisectors of weakly separable sets.
On the Cayley Factorization of Calotte Conditions.
On the chiral Archimedean solids.
On the constructibility of rational angles.
On the Contact Dimension of Graphs.
On the curves of constant relative width
On the derivation of the non-Euclidean angle of parallelism function.