1,122 research outputs found
Jones index theory for Hilbert C*-bimodules and its equivalence with conjugation theory
We introduce the notion of finite right (respectively left) numerical index
on a bimodule over C*-algebras A and B with a bi-Hilbertian structure. This
notion is based on a Pimsner-Popa type inequality. The right (respectively
left) index element of X can be constructed in the centre of the enveloping von
Neumann algebra of A (respectively B). X is called of finite right index if the
right index element lies in the multiplier algebra of A. In this case we can
perform the Jones basic construction. Furthermore the C*--algebra of bimodule
mappings with a right adjoint is a continuous field of finite dimensional
C*-algebras over the spectrum of Z(M(A)), whose fiber dimensions are bounded
above by the index. We show that if A is unital, the right index element
belongs to A if and only if X is finitely generated as a right module.
We show that bi-Hilbertian, finite (right and left) index C*-bimodules are
precisely those objects of the tensor 2-C*-category of right Hilbertian
C*-bimodules with a conjugate object, in the sense of Longo and Roberts, in the
same category.Comment: 59 pages, amste
On a q-difference Painlev\'e III equation: II. Rational solutions
Rational solutions for a -difference analogue of the Painlev\'e III
equation are considered. A Determinant formula of Jacobi-Trudi type for the
solutions is constructed.Comment: Archive version is already official. Published by JNMP at
http://www.sm.luth.se/math/JNMP
Third-order integrable difference equations generated by a pair of second-order equations
We show that the third-order difference equations proposed by Hirota,
Kimura and Yahagi are generated by a pair of second-order difference
equations. In some cases, the pair of the second-order equations are equivalent
to the Quispel-Robert-Thomson(QRT) system, but in the other cases, they are
irrelevant to the QRT system. We also discuss an ultradiscretization of the
equations.Comment: 15 pages, 3 figures; Accepted for Publication in J. Phys.
Smooth rationally connected threefolds contain all smooth curves
We show that if X is a smooth rationally connected threefold and C is a
smooth projective curve then C can be embedded in X. Furthermore, a version of
this property characterises rationally connected varieties of dimension at
least 3. We give some details about the toric case.Comment: Version 1 was called "Any smooth toric threefold contains all
curves". This version is completely rewritten and proves a much stronger
result, following suggestions of Janos Kolla
Crystal-field-induced magnetostrictions in the spin reorientation process of NdFeB-type compounds
Volume expansion associated with the spin reorientation
process of NdFeB-type compounds has been investigated in terms of
simple crystalline-electric-field (CEF) model. In this system,
is shown to be a direct measure of second order CEF energy. Calculated
anomalies in associated with the first-order magnetization
process of NdFeB are presented, which well reproduced the
observations.Comment: 2 pages, 2 figures, to appear in J. Magn. Magn. Mate
Log-aesthetic Curves as Similarity Geometric Analogue of Euler's Elasticae
In this paper we consider the log-aesthetic curves and their generalization
which are used in CAGD. We consider those curves under similarity geometry and
characterize them as stationary integrable flow on plane curves which is
governed by the Burgers equation. We propose a variational formulation of those
curves whose Euler-Lagrange equation yields the stationary Burgers equation.
Our result suggests that the log-aesthetic curves and their generalization can
be regarded as the similarity geometric analogue of Euler's elasticae
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