منابع مشابه
Almost Disjoint Large Subsets of Semigroups
There are several notions of largeness in a semigroup S that originated in topological dynamics. Among these are thick , central , syndetic and piecewise syndetic. Of these, central sets are especially interesting because they are partition regular and are guaranteed to contain substantial combinatorial structure. It is known that in (N,+) any central set may be partitioned into infinitely many...
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This paper uses the weighted L$_1-$norm to propose an algorithm for finding a well-dispersed subset of non-dominated solutions of multiple objective mixed integer linear programming problem. When all variables are integer it finds the whole set of efficient solutions. In each iteration of the proposed method only a mixed integer linear programming problem is solved and its optimal solutions gen...
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We answer a question of Gracia-Ferreira and Hrušák by constructing consistently a MAD family maximal in the Katětov order. We also answer several questions of Garcia-Ferreira.
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The collection of branches (maximal linearly ordered sets of nodes) of the tree ω (ordered by inclusion) forms an almost disjoint family (of sets of nodes). This family is not maximal – for example, any level of the tree is almost disjoint from all of the branches. How many sets must be added to the family of branches to make it maximal? This question leads to a series of definitions and result...
متن کاملAlmost disjoint families of connected sets
We investigate the question which (separable metrizable) spaces have a ‘large’ almost disjoint family of connected (and locally connected) sets. Every compact space of dimension at least 2 as well as all compact spaces containing an ‘uncountable star’ have such a family. Our results show that the situation for 1-dimensional compacta is unclear. 2004 Elsevier B.V. All rights reserved.
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ژورنال
عنوان ژورنال: Journal of Combinatorial Theory
سال: 1966
ISSN: 0021-9800
DOI: 10.1016/s0021-9800(66)80012-1