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1.
Satoru Fujishige 《Mathematical Programming》1984,29(2):125-141
The present paper shows that for any submodular functionf on a crossing family
with
, if the polyhedron
is nonempty, then there exist a unique distributive lattice
with
and a unique submodular function
with
such thatB(f) coincides with the base polyhedron
associated with the submodular system
. Here, iff is integer-valued, thenf
1 is also integer-valued.
Based on this fact, we also show the relationship between the independent-flow problem considered by the author and the minimum
cost flow problem considered by J. Edmonds and R. Giles. 相似文献
2.
It
and
are two families of pairwise disjoint simple closed curves in the plane such that each curve in
intersects each curve in
, then the total number of points of intersection in
is at least 2(m−1)n, where
, and this bound is best possible. We use this to show that the cartesian product of two 5-cycles has crossing number 15. 相似文献
3.
This article is in answer to a question posed by K. Borsuk [1]. There exists a locally connected continuum X which is movable
relative to the class of all spheres, but which is not 2-movable. We shall prove that the classes
of movable compacta coincide for the following
: 1) all polyhedra of dimension ⩽n, 2) all compacta of dimension ⩽n, and 3) all compacta of fundamental dimension ⩽n. We shall also prove that the movability of a compactum X is equivalent to its movability relative to the class of all polyhedra.
Translated from Matematicheskie Zametki, Vol. 21, No. 1, pp. 125–132, January, 1977.
The authors would like to thank Yu. M. Smirnov for the great interest he showed in this article. 相似文献
4.
Vicente Miquel 《Annals of Global Analysis and Geometry》1994,12(1):211-218
We prove that every connected compact Hopf hypersurface of a complex space form, contained in a geodesic ball of radius strictly smaller than the injectivity radius of, having constant mean curvature and with if if < 0 is a geodesic sphere of.Work partially supported by DGICYT Grant No. PB91-0324. 相似文献
5.
V. V. Peller 《Journal of Mathematical Sciences》1985,31(1):2709-2712
In this paper there is given a sufficient condition for a Hankel matrix F to belong to the space of Schur multipliers of all bounded operators in
2 (or, what is the same, to the tensor algebra V2). It is shown that ifw is a nonnegative function on T, such that is a sequence of integers, {Fi}j1 is a sequence of polynomials,) and, then FV2. It follows from this that under these conditions F is a multiplier of the space H1, i.e.,.Translated from Zapiski Nauchnykh Seminarov Leningradskogo Otdeleniya Matematicheskogo Instituta im. V. A. Steklova AN SSSR, Vol. 135, pp. 113–119, 1984 相似文献
6.
Automatic groups were introduced in connection with geometric problems, in particular with the study of fundamental groups
of 3-manifolds. In this article the class of automatic groups is extended to include the fundamental group of every compact
3-manifold which satisfies Thurston's geometrization conjecture. Toward this end, the class
of asynchronously
groups is introduced and studied, where
is an arbitrary full abstract family of languages. For example
may be the family of regular languagesReg, context-free languagesCF, or indexed languagesInd. The class
consists of precisely those groups which are asynchronously automatic. It is proved that
contains all of the above fundamental groups, but that
does not. Indeed a virtually nilpotent group belongs to
if and only if it is virtually abelian.
The first author was partially supported by NSF grant DMS-9203500 and FNRS (Suisse). He also wishes to thank the University
of Geneva for its hospitality while this paper was being written. The second author thanks the Institute for Advanced Study
for its hospitality while this paper was being written. 相似文献
7.
Z. A. Arushanyan 《Journal of Mathematical Sciences》1981,16(3):1161-1167
One finds conditions which ensure the possibility of weighted mean-square approximation of a vector-function defined on the
boundary of an n-dimensional domain
by vector-functions of the form
, where u is, the solution of the equation Δm
u=0 in
while∂/∂v denotes differentiation along the normal. The weight function is continuous and positive everywhere on
with the point
whose relative neighborhood
is contained in some (n-1)-dimensional plane. The solution of this approximation problem is closely related with a certain
uniqueness theorem for the solution of the Cauchy problem for the polyharmonic equation, also proved in the paper.
Translated from Zapiski Nauchnykh Seminarov Leningradskogo Otdeleniya Matematicheskogo Institute im. V. A. Steklova AN SSSR,
Vol. 65, pp. 164–171, 1976. 相似文献
8.
K. L. Malyshev 《Journal of Mathematical Sciences》1994,71(1):2281-2287
A representation of the algebra
(3)=t(3) S0(3, ) by differential Schaefer's operators is proposed, and an external algebra of
(3)-valued differential forms is constructed. The requirement of local gauge invariance is formulated in the model of the
(3)-valued field, which enables a group of gauge transformations of the continual theory of defects to be obtained.Translated from Zapiski Nauchnykh Seminarov Leningradskogo Otdeleniya Matematicheskogo Instituta im. V. A. Steklova AN SSSR, Vol. 190, pp. 173–184, 1991.I wish to thank V. N. Popov for his interest. 相似文献
9.
Giulio Tedeschi 《Annali dell'Universita di Ferrara》1978,24(1):167-173
Riassunto Sia
una proprietà degli anelli discende per fedele piattezza, ascende quando le fibre sono buone, di carattere locale e per cui
vale il criterio di Nagata. SeS è un dominio graduato noetheriano valgono alcune implicazioni per l'apertura del
in SpecS, ProjS e altri schemi collegati adS.
Summary Let be a property meaningful for rings which descends by faithful flatness, ascends when there are good fibers, with local character and for which Nagata's criterion holds. IfS is any graded noetherian domain some implications hold for the openness of the in SpecS, ProjS and other schemes related toS.相似文献
10.
For an arbitrary uniformly continuous completely positive semigroup (
t
:t0) on the space of bounded operators on a Hilbert space, we construct a family (U(t)t0) of unitary operators on a Hilbert space and a conditional expectation from to, such that, for arbitraryt0,. The unitary operatorsU(t) satisfy a stochastic differential equation involving a noncommutative generalisation of infinite dimensional Brownian motion. They do not form a semigroup.Part of this work was completed when the first author was visiting research associate at the Center for Relativity, Physics Department, The University of Texas at Austin, Austin, TX 78712, U.S.A., supported in part by NSF PHY 81-01381. 相似文献
11.
Evgeni Ja. Gabovič 《Semigroup Forum》1972,4(1):335-340
A semigroup S is calledE-semigroup (
-semigroup) if every (finitely generated) subsemigroup of S is an endomorphic image of S and Ē-semigroup (
-semigroup) if every subsemigroup of S is an E-semigroup
-semigroup. All classes X ε {Ē,
, E,
} are distinct even in the case of semilattices. It is established when a free band (semilattice) is an X-semigroup.
-,
- and Ē-chains and E-chains with identity or zero, Ē-and
, X-bands with identity and X-semigroups with identity and zero are found. 相似文献
12.
We prove a Schwarz lemma for a domain
in ℂ3 that arises in connection with a problem in H∞ control theory. We describe a class of automorphisms of
and determine the distinguished boundary of
We apply our Schwarz lemma to a special case of the μ-synthesis problem. 相似文献
13.
Jim Lawrence 《Discrete and Computational Geometry》1988,3(1):307-324
Given a collection of convex polytopes, let() denote the set of all convex transversals of. If and are two such collections, of finite cardinality, then there is a simple, arithmetical condition which holds precisely when ()=(). Another such condition, involving what we call the Sallee-Shephard mapping, characterizes those pairs and for which (())=().As these results are established, several distributive lattices involving convex sets are introduced, and relationships between their valuation modules are determined. In particular, it is proven that the Sallee-Shephard mapping is an isomorphism of the additive, abelian group of simple functions generated by the characteristic functions of the open, convex sets and that generated by those of the closed, convex sets. 相似文献
14.
P. P. Tammela 《Journal of Mathematical Sciences》1985,29(3):1306-1312
We prove the absolute finiteness of the number of faces (independent of the parameter) of Venkov's reduction domain (Izv. Akad. Nauk SSSR, Ser. Mat.4, 37–52 (1940)) ofn-ary positive quadratic forms. The casen=3 is given special consideration. We study the change of the reduction domain when changes along a line segment in the space of coefficients.Translated from Zapiski Nauchnykh Seminarov Leningradskogo Otdeleniya Matematicheskogo Instituta im. V. A. Steklova AN SSSR, Vol. 121, pp. 108–116, 1983. 相似文献
15.
Takaaki Nomura 《Annals of Global Analysis and Geometry》1994,12(1):237-260
We study the set of rankp idempotents in a topologically simple Hilbert Jordan algebra (JH-algebra for short). To produce the differential geometric structure on, we establish Jordan algebraic results concerning the structure of some two-generator subalgebras. We identify geodesics, the Riemannian distance and the sectional curvature of by using the Jordan algebraic structure. 相似文献
16.
We study the local solvability of the Cauchy-Dirichlet problem for the system
which describes the dynamics of an incompressible viscoelastic Kelvin-Voigt fluid. The configuration space of the problem
is described.
Translated fromMatematicheskie Zametki, Vol. 63, No. 3, pp. 442–450, March, 1998. 相似文献
17.
By a condenser in 相似文献
18.
Geoffrey S. Watson 《Annals of the Institute of Statistical Mathematics》1983,35(1):303-319
Summary A distribution on the unit sphere inℝ
q
with a densityf(‖x
v
‖) is considered where
is ans(<q) dimensional subspace andx
v
is the part ofx in
. For a large sample the estimation of
, a test that
and a test for rotational symmetry within
is given. For several samples with possibly different subspaces
but the samef, a test that
is given. For all tests power functions for contiguous alternatives are given. For the special density proportional to expk‖x
v
‖
2, additional results are given.
Research supported in part by a Contract with the Office of Naval Research N00014-81-K-0146 awarded to Princeton University,
Princeton, New Jersey 08544. 相似文献
19.
Given a self-concordant barrier function for a convex set
, we determine a self-concordant barrier function for the conic hull
of
. As our main result, we derive an “optimal” barrier for
based on the barrier function for
. Important applications of this result include the conic reformulation of a convex problem, and the solution of fractional
programs by interior-point methods. The problem of minimizing a convex-concave fraction over some convex set can be solved
by applying an interior-point method directly to the original nonconvex problem, or by applying an interior-point method to
an equivalent convex reformulation of the original problem. Our main result allows to analyze the second approach showing
that the rate of convergence is of the same order in both cases. 相似文献
20.
This paper introduces the concept of ‘symmetric centres’ of braided monoidal categories. LetH be a Hopf algebra with bijective antipode over a fieldk. We address the symmetric centre of the Yetter-Drinfel’d module category:
and show that a left Yetter-Drinfel’d moduleM belongs to the symmetric centre of
and only ifM is trivial. We also study the symmetric centres of categories of representations of quasitriangular Hopf algebras and give
a sufficient and necessary condition for the braid of,
Hℳ to induce the braid of
, or equivalently, the braid of
, whereA is a quantum commutativeH-module algebra 相似文献