Packing similar triangles into a triangle

There exists a triangle T and a number \frac{1}{2}$$ " align="middle" border="0"> such that any sequence of triangles similar to T with total area not greater than times the area of T can be packed into T.     

Packing of convex polytopes into a parallelepiped

This article deals with the problem of packing convex polytopes into a parallelepiped of minimal height. It is assumed that the polytopes are oriented, i.e. rotations are not permitted. A mathematical model of the problem is developed and peculiarities of them are addressed. Based on these peculiarities an exact method to compute local optimal solutions is constructed. This method uses a special modification of the Simplex method. Some examples are also given.     

Packing and covering the plane with translates of a convex polygon

A covering of the Euclidean plane by a polygon P is a system of translated copies of P whose union is the plane, and a packing of P in the plane is a system of translated copies of P whose interiors are disjoint. A lattice covering is a covering in which the translates are defined by the points of a lattice, and a lattice packing is defined similarly. We show that, given a convex polygon P with n vertices, the densest lattice packing of P in the plane can be found in O(n) time. We also show that the sparsest lattice covering of the plane by a centrally symmetric convex polygon can be solved in O(n) time. Our approach utilizes results from classical geometry that reduce these packing and covering problems to the problems of finding certain extremal enclosed figures within the polygon.     

Packing under convex quadratic constraints

Mathematical Programming - We consider a general class of binary packing problems with a convex quadratic knapsack constraint. We prove that these problems are $$mathsf {APX}$$ -hard to...     

Instability in a geometric parabolic equation on convex domain instability on convex domain

We prove that any non-constant smooth static solution to a geometric parabolic system is unstable, provided that the domain is convex. As the important applications, we shall consider the Landau-Lifshitz equation and the heat flow for harmonic map.     

On linearly convex domains with smooth boundaries

We establish that an arbitrary locally linearly convex domain with a smooth boundary is strongly linearly convex. Chernigov Pedagogic Institute, Chernigov. Translated from Ukrainskii Matematicheskii Zhurnal, Vol. 49, No. 11, pp. 1553–1556, November, 1997.     

Hyperbolically convex constricted domains

A subdomain G in the unit disk D is called hyperbolically convex if the non-euclidean segment between any two points in G also lies in G. We introduce the concept of constricted domain relative to the hyperbolic geometry of D and prove that a hyperbolic convex domain is constricted if and only if it is not a quasidisk. Also examples are given to illustrate these ideas.     

Linearly convex domains with singularities on the boundary

We present a topological classification of linearly convex domains with almost smooth boundary whose singularities lie in a hyperplane. We investigate sets with linearly convex boundary and the closures of linearly convex domains.     

Example of a strictly linear convex domain with nonrectifiable boundary

This work was partially supported by the Russian Foundation for Fundamental Research, Grant No. 93-011-258.     

Solvability of a convolution equation in convex domains

For an exponential functiona(z) we consider the convolutiona* x in the function space H(G), consisting of functions analytic in convex domains G. We obtain conditions (close to necessary and sufficient) on G and G₁ subject to which the equationa* (H(G₁)) = H(G) is satisfied.     

Moduli for pointed convex domains

Summary A moduli space for the class of pointed strictly linearly convex domains in ⁿ is obtained. It is shown that the space of pointed smoothly bounded strictly linearly convex domains with a fixed indicatrix is parameterized by a class of deformations of the CR structure of the boundary of the indicatrix. These deformations are constructed by using the circular representation of a domain to pull back its complex structure tensor to the indicatrix. A careful study of the pull back structure shows that the allowable deformations are parameterized by a class of complex Hamiltonian vector fields. The proof of this fact is based on the Folland-Stein estimates for the complex of the boundary of the indicatrix.The paper is related to one of László Lempert, Holomorphic invariants, normal forms and moduli space of convex domains. Ann. Math128, 47–78 (1988), where other modular data for pointed convex domains were constructed. A method of recovering Lempert's modular data from the deformation moduli is given.Oblatum 26-IX-1989 & 22-III-1990Partially supported by an NSERC grant.The second author wishes to thank the University of Toronto and the Mathematical Sciences Research Institute at Berkeley, where portions of the paper were written.     

Quasi-isometries in strongly convex domains

We provide examples of quasi-isometries for strongly convex domains in Cⁿ${\mathbb{C}}^n$ endowed with their Kobayashi distance.     

Quasihyperbolic geodesics in convex domains

We show that quasihyperbolic geodesics exist in convex domains in reflexive Banach spaces and that quasihyperbolic geodesies are quasiconvex in the norm metric in convex domains in all normed spaces.     

Decomposition of convex figures into similar pieces

If a convex plane figureP can be decomposed into finitely many nonoverlapping convex figures such that one of these pieces is similar toP, thenP is a polygon. Also, ifP can be decomposed into infinitely many nonoverlapping sets such that each of the pieces is similar toP, thenP is a polygon.     

Growth theorem of convex mappings on bounded convex circular domains

The growth theorem and the 1/2-covering theorem are obtained for the class of normalized biholomorphic convex mappings on bounded convex circular domains, which extend the corresponding results of Sufridge, Thomas, Liu, Gong, Yu, and Wang. The approach is new, which does not appeal to the automorphisms of the domains; and the domains discussed are rather general on which convex mappings can be studied, since the domain may not have a convex mapping if it is not convex. Project supported by the National Natural Science Foundation of China and the State Education Commission Doctoral Foundation.