Displaying similar documents to “On the jump number of lexicographic sums of ordered sets”

On monotone permutations of -cyclically ordered sets

Ján Jakubík (2006)

Czechoslovak Mathematical Journal

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For an -cyclically ordered set M with the -cyclic order C let P ( M ) be the set of all monotone permutations on M . We define a ternary relation C ¯ on the set P ( M ) . Further, we define in a natural way a group operation (denoted by · ) on P ( M ) . We prove that if the -cyclic order C is complete and C ¯ , then ( P ( M ) , · , C ¯ ) is a half cyclically ordered group.

Characterization of posets of intervals

Judita Lihová (2000)

Archivum Mathematicum

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If A is a class of partially ordered sets, let P ( A ) denote the system of all posets which are isomorphic to the system of all intervals of A for some A A . We give an algebraic characterization of elements of P ( A ) for A being the class of all bounded posets and the class of all posets A satisfying the condition that for each a A there exist a minimal element u and a maximal element v with u a v , respectively.

Selfduality of the system of convex subsets of a partially ordered set

Miron Zelina (1993)

Commentationes Mathematicae Universitatis Carolinae

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For a partially ordered set P let us denote by C o P the system of all convex subsets of P . It is found the necessary and sufficient condition (concerning P ) under which C o P (as a partially ordered set) is selfdual.