منابع مشابه
Convexity in Topological Affine Planes
We extend to topological affine planes the standard theorems of convexity, among them the separation theorem, the anti-exchange theorem, Radon’s, Helly’s, Carathéodory’s, and Kirchberger’s theorems, and the Minkowski theorem on extreme points. In a few cases the proofs are obtained by adapting proofs of the original results in the Euclidean plane; in others it is necessary to devise new proofs ...
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Let us observe that ∅ is ∅-valued and ∅ is onto. Next we state three propositions: (1) For every function f and for every set Y holds dom(Y f) = f−1(Y ). (2) For every function f and for all sets Y1, Y2 such that Y2 ⊆ Y1 holds (Y1 f)(Y2) = f(Y2). (3) Let S, T be topological structures and f be a function from S into T . If f is homeomorphism, then f−1 is homeomorphism. Let S, T be topological s...
متن کاملflambement des structures planes
l'utilisation de nouvaux materiaux aux caracteristiques mecaniques elevtes et le perfectionement continu des methodes de calcu1,incitent les constructeur a edifier des structures de plus cn plus elancees , de ce fait le probleme du flambement prend une importance sans cesse accrue. la prtsente etude se rapporte a etablir les equations intrinseques d'une poutre droite a section constan...
متن کاملOmittable Planes
In analogy to omittable lines in the plane, we initiate the study of omittable planes in 3-space. Given a collection of n planes in real projective 3-space, a plane Π is said to be omittable if Π is free of ordinary lines of intersection – in other words, if all the lines of intersection of Π with other planes from the collection come at the intersection of three or more planes. We provide two ...
متن کاملStabbing Planes
We introduce and develop a new semi-algebraic proof system, called Stabbing Planes that is in the style of DPLL-based modern SAT solvers. As with DPLL, there is only one rule: the current polytope can be subdivided by branching on an inequality and its “integer negation.” That is, we can (nondeterministically choose) a hyperplane ax ≥ b with integer coefficients, which partitions the polytope i...
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ژورنال
عنوان ژورنال: Advances in Mathematics
سال: 1967
ISSN: 0001-8708
DOI: 10.1016/s0001-8708(67)80002-1