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Abstract : |
Summary. In the beginning of this article we define the choice function of a nonempty set family that does not contain /0 as introduced in [6, pages 88?89]. We define order of a set as a relation being reflexive, antisymmetric and transitive in the set, partially ordered set as structure non-empty set and order of the set, chains, lower and upper cone of a subset, initial segments of element and subset of partially ordered set. Some theorems that belong rather to [5] or [12] are proved., |
