Sets in the plane with many concyclic subsets.
Sets of points determining only acute angles and some related colouring problems.
Seules les quadriques admettent des caustiques
Several observations about Maneeals - a peculiar system of lines
For an arbitrary triangle ABC and an integer n we define points Dn, En, Fn on the sides BC, CA, AB respectively, in such a manner that |AC|n|AB|n=|CDn||BDn|,|AB|n|BC|n=|AEn||CEn|,|BC|n|AC|n=|BFn||AFn|. Cevians ADn, BEn, CFn are said to be the Maneeals of order n. In this paper we discuss some properties of the Maneeals and related objects.
Shape tiling.
Sharpening on Mircea's inequality.
Sharply 2-transitive sets of permutations and groups of affine projectivities.
Shells of monotone curves
We determine in the form of curves corresponding to strictly monotone functions as well as the components of affine connections for which any image of under a compact-free group of affinities containing the translation group is a geodesic with respect to . Special attention is paid to the case that contains many dilatations or that is a curve in . If is a curve in and is the translation group then we calculate not only the components of the curvature and the Weyl tensor but...
Shodná zobrazení v prostoru
Sigma models with non-commuting complex structures and extended supersymmetry
We discuss additional supersymmetries for supersymmetric non-linear sigma models described by left and right semichiral superfields.
Similarity motions in with plane trajectories
In this paper the author finds and describes all similarity space motions, which have only plane trajectories of points. All such motions are explicitly expressed. They are of 5 types, all of them cylindrical. Trajectories are conic sections (3 types) or arbitrary plane curves (2 types).
Simple counter examples for the unsolvability of the Fermat- and Steiner-Weber-problem by compass and ruler.
Simple Groups and Möbius Planes of Even Order.
Simplicial finite elements in higher dimensions
Over the past fifty years, finite element methods for the approximation of solutions of partial differential equations (PDEs) have become a powerful and reliable tool. Theoretically, these methods are not restricted to PDEs formulated on physical domains up to dimension three. Although at present there does not seem to be a very high practical demand for finite element methods that use higher dimensional simplicial partitions, there are some advantages in studying the methods independent of the...
Simplicial maps from the 3-sphere to the 2-sphere.
Skewsquares in quadratical quasigroups
The concept of pseudosquare in a general quadratical quasigroup is introduced and connections to some other geometrical concepts are studied. The geometrical presentations of some proved statements are given in the quadratical quasigroup .
Sliding subspace design based on linear matrix inequalities
In this work, an alternative for sliding surface design based on linear and bilinear matrix inequalities is proposed. The methodology applies for reduced and integral sliding mode control, both continuous- and discrete-time; it takes advantage of the Finsler's lemma to provide a greater degree of freedom than existing approaches for sliding subspace design. The sliding surfaces thus constructed are systematically found via convex optimization techniques, which are efficiently implemented in commercially...
Sobre la geometría de la diferencia simétrica.
Soddyho kružnice
Soddyho kružnice, které jsou řešením speciálního případu Apollóniových úloh, upoutaly pozornost matematické komunity především poté, co byly roku 1936 některé jejich vlastnosti publikovány Frederickem Soddym ve formě básně. Studovány však byly již v 17. století. Kromě historie popíšeme jejich konstrukci, vyjádříme jejich poloměry a představíme některé s nimi související geometrické útvary.
Software for Geometry