Coordinatization of parallel systems
Coordinatization of parallel systems. II.
Coordinatization of projective planes by special planar ternary rings
Correction to "A Class of Rank Three Affine Planes".
Correction to "Collineations of Finite Projective Spaces as Permutations on the Sets of Dual Subspaces".
Correction to "On a functional equation arising from hyperbolic geometry", Volume 21 (1980), 113-116.
Correction to "Partial Spreads in Finite Projective Spaces and Partial Designs".
Countable Decompositions of R2 and R3 .
Countably convex sets
We investigate countably convex subsets of Banach spaces. A subset of a linear space is countably convex if it can be represented as a countable union of convex sets. A known sufficient condition for countable convexity of an arbitrary subset of a separable normed space is that it does not contain a semi-clique [9]. A semi-clique in a set S is a subset P ⊆ S so that for every x ∈ P and open neighborhood u of x there exists a finite set X ⊆ P ∩ u such that conv(X) ⊈ S. For closed sets this condition...
Counting all equilateral triangles in .
Counting Types of Rigid Frameworks.
Courbure d'une courbe plane donnée par son équation tangentielle
Court’s conjecture on points in
Covering the plane with sprays
For any three noncollinear points c₀,c₁,c₂ ∈ ℝ², there are sprays S₀,S₁,S₂ centered at c₀,c₁,c₂ that cover ℝ². This improves the result of de la Vega in which c₀,c₁,c₂ were required to be the vertices of an equilateral triangle.
Coxeter classes of unitary reflection groups.
Criteria for two-dimensional circle planes.
Critical configurations of planar robot arms
It is known that a closed polygon P is a critical point of the oriented area function if and only if P is a cyclic polygon, that is, P can be inscribed in a circle. Moreover, there is a short formula for the Morse index. Going further in this direction, we extend these results to the case of open polygonal chains, or robot arms. We introduce the notion of the oriented area for an open polygonal chain, prove that critical points are exactly the cyclic configurations with antipodal endpoints and derive...
Crooked planes.
Cross ratios of points and lines in Moufang planes.
Čtyry poučky o ellipsách a ellipsoidech