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Solving a ± b = 2c in elements of finite sets

Vsevolod F. Lev, Rom Pinchasi (2014)

Acta Arithmetica

We show that if A and B are finite sets of real numbers, then the number of triples (a,b,c) ∈ A × B × (A ∪ B) with a + b = 2c is at most (0.15+o(1))(|A|+|B|)² as |A| + |B| → ∞. As a corollary, if A is antisymmetric (that is, A ∩ (-A) = ∅), then there are at most (0.3+o(1))|A|² triples (a,b,c) with a,b,c ∈ A and a - b = 2c. In the general case where A is not necessarily antisymmetric, we show that the number of triples (a,b,c) with a,b,c ∈ A and a - b = 2c is at most (0.5+o(1))|A|². These estimates...

Solving the sensor cover energy problem via integer linear programming

Pingke Li (2021)

Kybernetika

This paper demonstrates that the sensor cover energy problem in wireless communication can be transformed into a linear programming problem with max-plus linear inequality constraints. Consequently, by a well-developed preprocessing procedure, it can be further reformulated as a 0-1 integer linear programming problem and hence tackled by the routine techniques developed in linear and integer optimization. The performance of this two-stage solution approach is evaluated on a set of randomly generated...

Some characterization of locally nonconical convex sets

Witold Seredyński (2004)

Czechoslovak Mathematical Journal

A closed convex set Q in a local convex topological Hausdorff spaces X is called locally nonconical (LNC) if for every x , y Q there exists an open neighbourhood U of x such that ( U Q ) + 1 2 ( y - x ) Q . A set Q is local cylindric (LC) if for x , y Q , x y , z ( x , y ) there exists an open neighbourhood U of z such that U Q (equivalently: b d ( Q ) U ) is a union of open segments parallel to [ x , y ] . In this paper we prove that these two notions are equivalent. The properties LNC and LC were investigated in [3], where the implication L N C L C was proved in general, while...

Some geometric properties of typical compact convex sets in Hilbert spaces

F. de Blasi (1999)

Studia Mathematica

An investigation is carried out of the compact convex sets X in an infinite-dimensional separable Hilbert space , for which the metric antiprojection q X ( e ) from e to X has fixed cardinality n+1 ( n arbitrary) for every e in a dense subset of . A similar study is performed in the case of the metric projection p X ( e ) from e to X where X is a compact subset of .

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