A free group acting without fixed points on the rational unit sphere
A free group of piecewise linear transformations
We prove the following conjecture of J. Mycielski: There exists a free nonabelian group of piecewise linear, orientation and area preserving transformations which acts on the punctured disk {(x,y) ∈ ℝ²: 0 < x² + y² < 1} without fixed points.
A further remark concerning Nagel cevians.
A general coordinatization principle for projective planes with comparison of Hall and Hughes frames and with examples of generalized oval frames
A generalization of a construction due to Van Nypelseer.
A Generalization of a Theorem of Sylvester on the Lines Determined by a Finite Point Set.
A generalization of a two triangle inequality.
A Generalization of Hadwiger's Transversal Theorem to Intersecting Sets.
A generalization of Hermite collineation to the n-dimensional space
A generalization of Nagel's middlespoint.
A geometric analysis of dynamical systems with singular Lagrangians
We study dynamics of singular Lagrangian systems described by implicit differential equations from a geometric point of view using the exterior differential systems approach. We analyze a concrete Lagrangian previously studied by other authors by methods of Dirac’s constraint theory, and find its complete dynamics.
A Geometric Characterization of Generalized Moulton Planes.
A Geometric Characterization of Moufang Hexagons.
A geometric inequality involving a mobile point in the place of the triangle.
A geometric inequality of the generalized Erdős-Mordell type.
A Geometric Realization Without Self-Intersections Does Exist for Dyck's Regular Map.
A geometric theory of harmonic and semi-conformal maps
We describe for any Riemannian manifold M a certain scheme M L, lying in between the first and second neighbourhood of the diagonal of M. Semi-conformal maps between Riemannian manifolds are then analyzed as those maps that preserve M L; harmonic maps are analyzed as those that preserve the (Levi-Civita-) mirror image formation inside M L.
A Geometric Theory of Surface Area.
A Geometric Theory of Surface Area.
A Geometric Theory of Surface Area. III.