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101.
杨胜良 《纯粹数学与应用数学》1996,12(2):57-60
证明了发下结果;格序群的扭自由根式全体构成一个完备格县这个格满足并无限分配律,所有主扭自由根式构成这个格的一个理想。 相似文献
102.
103.
We study into the relationship between constructivizations of an associative commutative ring K with unity and constructivizations of matrix groups GL
n(K) (general), SL
n(K) (special), and UT
n(K) (unitriangular) over K. It is proved that for n 3, a corresponding group is constructible iff so is K. We also look at constructivizations of ordered groups. It turns out that a torsion-free constructible Abelian group is orderly constructible. It is stated that the unitriangular matrix group UT
n(K) over an orderly constructible commutative associative ring K is itself orderly constructible. A similar statement holds also for finitely generated nilpotent groups, and countable free nilpotent groups. 相似文献
104.
It will be shown that a normed partially ordered vector space is linearly, norm, and order isomorphic to a subspace of a normed Riesz space if and only if its positive cone is closed and its norm p satisfies p(x)p(y) for all x and y with -yxy. A similar characterization of the subspaces of M-normed Riesz spaces is given. With aid of the first characterization, Krein's lemma on directedness of norm dual spaces can be directly derived from the result for normed Riesz spaces. Further properties of the norms ensuing from the characterization theorem are investigated. Also a generalization of the notion of Riesz norm is studied as an analogue of the r-norm from the theory of spaces of operators. Both classes of norms are used to extend results on spaces of operators between normed Riesz spaces to a setting with partially ordered vector spaces. Finally, a partial characterization of the subspaces of Riesz spaces with Riesz seminorms is given. 相似文献
105.
V. V. Bludov 《Algebra and Logic》2003,42(5):304-317
We prove a theorem saying that in finitely generated linearly ordered metabelian groups there exists a finite system of normal convex subgroups satisfying orderability conditions for groups, and an embedding theorem for linearly ordered metabelian groups whose initial linear orders extend to -divisible linearly ordered metabelian ones. As a consequence, it is stated that orderable metabelian groups are embedded, with extension of all their linear orders, in -divisible orderable metabelian groups. 相似文献
106.
V. F. Murzina 《Algebra and Logic》2003,42(3):181-191
A modal logic associated with the
-spaces introduced by Ershov is examined. We construct a modal calculus that is complete w.r.t. the class of all strictly linearly ordered
-frames, and the class of all strictly linearly ordered
-frames. 相似文献
107.
J.A. Hodges P. Bonville A. Forget J.P. Sanchez P. Vulliet M. Rams K. Królas 《The European Physical Journal B - Condensed Matter and Complex Systems》2003,33(2):173-181
Using 170Yb and 155Gd M?ssbauer measurements down to ∼ 0.03 K, we have examined the semiconducting pyrochlore Yb2Mo2O7 where the Mo intra-sublattice interaction is anti-ferromagnetic and the metallic pyrochlore Gd2Mo2O7 where this interaction is ferromagnetic. Additional information was obtained from susceptibility, magnetisation and 172Yb perturbed angular correlation measurements. The microscopic measurements evidence lattice disorder which is important in
Yb2Mo2O7 and modest in Gd2Mo2O7. Magnetic irreversibilities occur at 17 K in Yb2Mo2O7 and at 75 K in Gd2Mo2O7 and below these temperatures the rare earths carry magnetic moments which are induced through couplings with the Mo sublattice.
In Gd2Mo2O7, we observe the steady state Gd hyperfine populations at 0.027 K are out of thermal equilibrium, indicating that Gd and Mo
spin fluctuations persist at very low temperatures. Frustration is thus operative in this essentially isotropic pyrochlore
where the dominant Mo intra-sublattice interaction is ferromagnetic.
Received 13 January 2003 Published online 4 June 2003
RID="a"
ID="a"e-mail: hodges@drecam.saclay.cea.fr 相似文献
108.
Yun S. Song 《Annals of Combinatorics》2003,7(3):365-379
We study subtree-prune-and-regraft (SPR) operations on
leaf-labelled rooted binary trees, also known as rooted binary phylogenetic trees.
This study is motivated by the problem of
graphically representing evolutionary histories of biological sequences subject to recombination.
We investigate some basic properties of the induced SPR-metric on the space
of leaf-labelled
rooted binary trees with n leaves. In contrast to the case of
unrooted trees, the number |U(T)| of trees in
which are one SPR operation away from a given tree
depends on the
topology of T. In this paper, we construct recursion relations which allow one to determine the
unit-neighbourhood size |U(T)| efficiently for any tree topology. In fact, using the recursion
relations we are able to derive a simple closed-form formula for the unit-neighbourhood size.
As a corollary, we construct sharp upper and lower bounds on the size of unit-neighbourhoods
and investigate the diameter of
.
Lastly, we consider an enumeration problem relevant to population genetics.AMS Subject Classification: 05C05, 92D15. 相似文献
109.
The construction of the sum of a direct (semilattice ordered) system of algebras introduced by J. Plonka – later known as the Plonka sum – is one of the most important methods of composition in universal algebra, having a number of applications in different algebraic theories, such as semigroup theory, semiring theory, etc. In this paper we present a more general way for constructing algebras with involution, that is, algebraic systems equipped with a unary involutorial operation which is at the same time an antiautomorphism of the underlying algebra. It is the sum – involutorial Plonka sum, as we call it – of an involution semilattice ordered system of algebras. We investigate its basic properties, as well as the problem of its subdirect decomposition. 相似文献
110.
Harold R. Bennett Robert W. Heath David J. Lutzer 《Proceedings of the American Mathematical Society》2001,129(3):931-939
In this paper we study the question ``When does a perfect generalized ordered space have a -closed-discrete dense subset?' and we characterize such spaces in terms of their subspace structure, -mappings to metric spaces, and special open covers. We also give a metrization theorem for generalized ordered spaces that have a -closed-discrete dense set and a weak monotone ortho-base. That metrization theorem cannot be proved in ZFC for perfect GO-spaces because if there is a Souslin line, then there is a non-metrizable, perfect, linearly ordered topological space that has a weak monotone ortho-base.