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On the dynamics of (left) orderable groups

Andrés Navas (2010)

Annales de l’institut Fourier

We develop dynamical methods for studying left-orderable groups as well as the spaces of orderings associated to them. We give new and elementary proofs of theorems by Linnell (if a left-orderable group has infinitely many orderings, then it has uncountably many) and McCleary (the space of orderings of the free group is a Cantor set). We show that this last result also holds for countable torsion-free nilpotent groups which are not rank-one Abelian. Finally, we apply our methods to the case of braid...

On the embedding of ordered semigroups into ordered group

Mohammed Ali Faya Ibrahim (2004)

Czechoslovak Mathematical Journal

It was shown in [7] that any right reversible, cancellative ordered semigroup can be embedded into an ordered group and as a consequence, it was shown that a commutative ordered semigroup can be embedded into an ordered group if and only if it is cancellative. In this paper we introduce the concept of L -maher and R -maher semigroups and use a technique similar to that used in [7] to show that any left reversible cancellative ordered L or R -maher semigroup can be embedded into an ordered group.

On the L -valued categories of L - E -ordered sets

Olga Grigorenko (2012)

Kybernetika

The aim of this paper is to construct an L -valued category whose objects are L - E -ordered sets. To reach the goal, first, we construct a category whose objects are L - E -ordered sets and morphisms are order-preserving mappings (in a fuzzy sense). For the morphisms of the category we define the degree to which each morphism is an order-preserving mapping and as a result we obtain an L -valued category. Further we investigate the properties of this category, namely, we observe some special objects, special...

On the maximal subgroup of the sandwich semigroup of generalized circulant Boolean matrices

Jinsong Chen, Yi Jia Tan (2006)

Czechoslovak Mathematical Journal

Let n be a positive integer, and C n ( r ) the set of all n × n r -circulant matrices over the Boolean algebra B = { 0 , 1 } , G n = r = 0 n - 1 C n ( r ) . For any fixed r -circulant matrix C ( C 0 ) in G n , we define an operation “ * ” in G n as follows: A * B = A C B for any A , B in G n , where A C B is the usual product of Boolean matrices. Then ( G n , * ) is a semigroup. We denote this semigroup by G n ( C ) and call it the sandwich semigroup of generalized circulant...

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