共查询到20条相似文献,搜索用时 26 毫秒
1.
V. V. Makeev 《Journal of Mathematical Sciences》2007,140(4):558-563
Let ℝn be the n-dimensional Euclidean space, and let { · } be a norm in Rn. Two lines ℓ1 and ℓ2 in ℝn are said to be { · }-orthogonal if their { · }-unit direction vectors e
1 and e
2 satisfy {e
1 + e
2} = {e
1 − e
2}. It is proved that for any two norms { · } and { · }′ in ℝn there are n lines ℓ1, ..., ℓn that are { · }-and { · }′-orthogonal simultaneously. Let
be a continuous function on the unit sphere
with center O. It is proved that there exists an (n − 1)-cube C centered at O, inscribed in
, and such that all sums of values of f at the vertices of (n − 3)-faces of C are pairwise equal. If the function f is even,
then there exists an n-cube with the same properties. Furthermore, there exists an orthonormal basis e
1, ..., e
n such that for 1 ≤ i ≤ j ≤ n we have
. Bibliography: 8 titles.
__________
Translated from Zapiski Nauchnykh Seminarov POMI, Vol. 329, 2005, pp. 107–117. 相似文献
2.
Friedrich W. Bauer 《Journal of Mathematical Sciences》2008,148(2):175-191
In a category with homotopy
(Definition 1.1), one can define a natural concept of (co)fibrations and weak equivalences (Sec. 2) such that some properties
of a closed model category hold. If
is a complete and cocomplete category (with respect to finite limits) with simplicial homotopy (Definition 1.3), one achieves a full closed model structure in
(Theorem 4.6). For each category with homotopy
, there exists a category with simplicial homotopy
(see Sec. 5) (the simplicial envelope of
). If
is already a complete category with simplicial homotopy, then
is Quillen equivalent to
(Theorem 5.9).
__________
Translated from Sovremennaya Matematika i Ee Prilozheniya (Contemporary Mathematics and Its Applications), Vol. 41, Topology
and Its Applications, 2006. 相似文献
3.
N. A. Shirokov 《Journal of Mathematical Sciences》2005,129(4):4083-4086
Let
n be the unit ball in ℂn, n ≥ 2. Let Tα = {z ∈
n : (z, a) = |a|2} for a ∈
n and denote
for a discrete set A in
n. We find a sharp necessary condition for a set A to be a part of the zero-set for a function in H∞(
n). Bibliography 4 titles.__________Translated from Zapiski Nauchnykh Seminarov POMI, Vol. 303, 2003, pp. 272–278. 相似文献
4.
We observe an unknown function of infinitely many variables f = f(t), t = (t1, ..., tn, ... ) ∈, [0, 1]∞, in the Gaussian white noise of level ε > 0. We suppose that in each variable there exists a 1-periodical σ-smooth extension
of the function f(t) to IR
∞. Taking a quantity σ > 0 and a positive sequence a = {ak}, we consider the set
that consists of functions f such that
. We consider the cases ak = kα and ak = exp(λk), α > 0, λ > 0. We would like to estimate a function f ∈
or to test the null hypothesis H0: f = 0 against the alternatives f ∈
, where the set
consists of functions f ∈
such that ∥f∥2 ≥ r. In the estimation problem, we obtain the asymptotics (as ε → 0) of the minimax quadratic risk. In the detection problem,
we study the sharp asymptotics of minimax separation rates f
ɛ
*
that provide distiguishability in the problems. Bibliography: 12 titles.
__________
Translated from Zapiski Nauchnykh Seminarov POMI, Vol. 328, 2005, pp. 91–113. 相似文献
5.
Research on finite solvable groups with C-closed invariant subgroups has given rise to groups structured as follows. Let p,
q1, q2, ..., qm be distinct primes, ni be the exponent of p modulo qi, and n be the exponent of p modulo
. Then G = Pλ〈x〉, where P is a group and
; Zi; here, Zi and P/Z(P) are elementary Abelian groups of respective orders
and pn, |x| = r, the element x acts irreducibly on P/Z(P) and on each of the subgroups Zi, and
. We state necessary and sufficient conditions for such groups to exist.
__________
Translated from Algebra i Logika, Vol. 45, No. 4, pp. 379–389, July–August, 2006. 相似文献
6.
A. M. Arkhipov 《Journal of Mathematical Sciences》2006,139(6):7013-7024
In this paper, we consider the Kuramoto-Sivashinskii equation on the multidimensional torus with a Riemannian metric:
where
. For this equation the theorem on energy transfer holds. It is formulated in the following way. Let
be the Fourier expansion of the function u. Denote by P
N
and P
N
⊥
the operators of rejection of the “leading” and, respectively, “lowest” terms of the Fourier expansion (harmonics), i.e.,
.
For any ρ > 0,N ∈ ℕ, s ≥ n/2+5, and λ ∈ (0, 1), there exists R such that for any function. ϕ ∈
lying outside the ball
in the ball
, there exists an instant of time t ∈ (0, 1) such that g
KS
t
ϕ=ψ and
. Here, R is a constant depending on the metric (g), n
s
is the sth Sobolev norm, and
is the C
1-norm.
__________
Translated from Sovremennaya Matematika i Ee Prilozheniya (Contemporary Mathematics and Its Applications), Vol. 24, Dynamical
Systems and Optimization, 2005. 相似文献
7.
V. V. Makeev 《Journal of Mathematical Sciences》2005,131(1):5395-5400
Let ABCDE be a pentagon inscribed in a circle. It is proved that if
is a C4-generic smooth convex planar oval with four vertices (stationary points of curvature), then there are two similarities φ
such that the quadrangle φ(ABCD) is inscribed in
and the point φ(E)lies inside
, as well as two similarities ψ such that the quadrangle ψ(ABCD) is inscribed in
and ψ(E)lies outside
. Itisalsoprovedthatif n is odd, then any smoothly embedded circle γ ↪ ℝn contains the vertices of an equilateral (n + 1)-link polygonal line lying in a hyperplane of ℝn. Bibliography: 7 titles.
__________
Translated from Zapiski Nauchnykh Seminarov POMI, Vol. 299, 2003, pp. 241–251. 相似文献
8.
N. V. Smorodina 《Journal of Mathematical Sciences》2007,145(2):4914-4922
Let ξ(t), t ∈ [0, 1], be a strictly stable process with an index of stability α ∈ (0, 2). By
we denote the law of ξ in the Skorokhod space
[0,1]. For arbitrary strictly stable process ξ, we construct a semigroup of transformations of
[0, 1] for which the measure
is quasi-invariant. For strictly stable processes with positive and negative jumps, we construct a group of transformations
of
[0, 1] for which the measure
is quasi-invariant. In the symmetric case, this group is a group of invariant transformations. Bibliography: 10 titles.
__________
Translated from Zapiski Nauchnykh Seminarov POMI, Vol. 339, 2006, pp. 135–149. 相似文献
9.
A. Ayad 《Journal of Mathematical Sciences》2006,134(5):2325-2339
An algorithm is constructed for the absolute factorization of polynomials with algebraically independent parametric coefficients.
It divides the parameter space into pairwise disjoint pieces such that the absolute factorization of polynomials with coefficients
in each piece is given uniformly. Namely, for each piece there exist a positive integer l ≤ d, l variables C1, ..., Cl algebraically independent over the ground field F, and rational functions bJ,j of the parameters and of the variables C1, ..., Cl such that for any parametric polynomial f with coefficients in this piece, there exist c1, ...,
with f = Π
j
G
j
where G
j
= Σ|J|
B
J,j
Z
J
is absolutely irreducible. Here Z = (Z0, ..., Zn) are the variables of f, each BJ,j is the value of bJ,j at the coefficients of f and c1, ..., cl, and
denotes the algebraic closure of F. The number of pieces does not exceed (2d2+1)2n+3d+5, and the algorithm performs
arithmetic operations in F (thus the number of operations is exponential in the number r = (
n+1
n+1+d
) of coefficients of f), and its binary complexity is bounded by
if F = ℚ and by
if
, where d is an upper bound on the degrees of polynomials. The techniques used include the Hensel lemma and the quantifier
elimination in the theory of algebraically closed fields. Bibliography: 20 titles.
Published in Zapiski Nauchnykh Seminarov POMI, Vol. 316, 2004, pp. 5–29. 相似文献
10.
Let {\bold x}[] be a stationary Gaussian process with zero mean and spectral density f, let
be the -algebra induced by the random variables {\bold x}[], D(R1), and let
t, t > 0, be the -algebra induced by the random variables x[],supp [-t,t]. Denote by
(f) the Gaussian measure on
generated by {\bold x}. Let
t(f) be the restriction of
(f) to
t. Let f and g be nonnegative functions such that the measures
t(f) and
t(g) are absolutely continuous. Put
For a fixed g(u) and for f(u)= ft(u) close to g(u) in some sense, the asymptotic normality of
t(f,g) is proved under some regularity conditions. Bibliography: 14 titles. 相似文献
11.
Given a unital C*-algebra
and a right C*-module
over
, we consider the problem of finding short smooth curves in the sphere
= {x ∈
: 〈x, x〉 = 1}. Curves in
are measured considering the Finsler metric which consists of the norm of
at each tangent space of
. The initial value problem is solved, for the case when
is a von Neumann algebra and
is selfdual: for any element x
0 ∈
and any tangent vector ν at x
0, there exists a curve γ(t) = e
tZ
(x
0), Z ∈
, Z* = −Z and ∥Z∥ ≤ π, such that γ(0) = x
0 and
(0) = ν, which is minimizing along its path for t ∈ [0, 1]. The existence of such Z is linked to the extension problem of selfadjoint operators. Such minimal curves need not be unique. Also we consider the
boundary value problem: given x
0, x
1 ∈
, find a curve of minimal length which joins them. We give several partial answers to this question. For instance, let us
denote by f
0 the selfadjoint projection I − x
0 ⊗ x
0, if the algebra f
0
f
0 is finite dimensional, then there exists a curve γ joining x
0 and x
1, which is minimizing along its path.
相似文献
12.
D. M. Smirnov 《Algebra and Logic》2005,44(5):348-352
We deal with varieties with one basic operation f(x1,...,xn) and one defining identity f(x1,..., xn) = f(xπ(1),...,xπ(n)), where π is a permutation whose cyclic set consists of distinct primes p1,...,pr, with the sum p1+...+pr = n. Their interpretability types, together with the greatest element 1 in a lattice
int, are said to be arithmetic. It is proved that the arithmetic types constitute a distributive lattice
ar, which is dual to a lattice Sub
fΠ of finite subsets of the set Π of all primes. It is shown that for n ⩾ 2, the poset
ar(
n) of arithmetic types defined by permutations in
n, for n fixed, is a lattice iff n = 2, 3, 4, 6, 8, 9, 11.
__________
Translated from Algebra i Logika, Vol. 44, No. 5, pp. 622–630, September–October, 2005. 相似文献
13.
N. V. Smorodina 《Journal of Mathematical Sciences》2007,147(4):6950-6957
Let ξ(t), t ∈ [0, 1], be a jump Lévy process. We denote by
the law of ξ in the Skorokhod space
[0, 1]. Under some nondegeneracy condition on the Lévy measure Λ of the process, we construct a group of
-preserving transformations of the space
[0, 1]. Bibliography: 11 titles.
__________
Translated from Zapiski Nauchnykh Seminarov POMI, Vol. 341, 2007, pp. 175–188. 相似文献
14.
O. V. Kulikova 《Journal of Mathematical Sciences》2007,142(2):1942-1948
Under the condition of asphericity of a quotient group
, mutual commutants of the form
in hyperbolic groups G are investigated together with the structure of central subgroups
in central extensions
of
. In particular, quotients of the form G/[g
m
, G] are considered, where g is an element of infinite order from a hyperbolic group G and m is sufficiently large (depending on g).
__________
Translated from Fundamentalnaya i Prikladnaya Matematika, Vol. 11, No. 2, pp. 115–125, 2005. 相似文献
15.
V. G. Zhuravlev 《Journal of Mathematical Sciences》2006,137(2):4658-4672
For the two-dimensional torus
, we construct the Rauzy tilings d0 ⊃ d1 ⊃ … ⊃ dm ⊃ …, where each tiling dm+1 is obtained by subdividing the tiles of dm. The following results are proved. Any tiling dm is invariant with respect to the torus shift S(x) = x+
mod ℤ2, where ζ−1 > 1 is the Pisot number satisfying the equation x3− x2−x-1 = 0. The induced map
is an exchange transformation of Bmd ⊂
, where d = d0 and
. The map S(m) is a shift of the torus
, which is affinely isomorphic to the original shift S. This means that the tilings dm are infinitely differentiable. If ZN(X) denotes the number of points in the orbit S1(0), S2(0), …, SN(0) belonging to the domain Bmd, then, for all m, the remainder rN(Bmd) = ZN(Bmd) − N ζm satisfies the bounds −1.7 < rN(Bmd) < 0.5. Bibliography: 10 titles.
__________
Translated from Zapiski Nauchnykh Seminarov POMI, Vol. 322, 2005, pp. 83–106. 相似文献
16.
Milan Jasem 《Mathematica Slovaca》2007,57(2):107-118
In the paper isometries in pseudo MV-algebras are investigated. It is shown that for every isometry f in a pseudo MV-algebra
= (A, ⊕, −, ∼, 0, 1) there exists an internal direct decomposition
of
with
commutative such that
and
for each x ∈ A.
On the other hand, if
is an internal direct decomposition of a pseudo MV-algebra
= (A, ⊕, −, ∼, 0, 1) with
commutative, then the mapping g: A → A defined by
is an isometry in
and
.
相似文献
17.
Given H≥0 and bounded convex curves α1, ...,⇌n, α in the plane z=0 bounding domains D1, …, Dn, D, respectively, with
if i ∈ j and with Di ⊂ D, we obtain several results proving the existence of a constanth depending only on H and on the geometry of the curves
αi, α such that the Dirichlet problem for the constant mean curvature H equation:
where
may accept or not a solution. 相似文献
18.
N. I. Osetinskii 《Computational Mathematics and Modeling》2008,19(1):45-56
We consider the classification of generalized linear controllable systems over the field
= ℂ or
= ℝ under transformations defined by the action of the group GL
n
(
) × GL
n
(
). We review the recent results of Cobb, Helmke, Shayman, Zhou, Hinrichsen, O’Halloran, and others on the geometric structure
of the set of orbits C
n,m
(
) of generalized linear controllable systems, which in particular prove smoothness, compactness, and projectivity of C
n,m
(
) and evaluate its dimension. We show that C
n,m
(
) is a natural compactification of the set of orbits of ordinary linear controllable systems ∑
n,m
(
) and the boundary C
n,m
(
) − ∑
n,m
(
) consists of the orbits of singular generalized systems.
__________
Translated from Nelineinaya Dinamika i Upravlenie, No. 4, pp. 153–166, 2004. 相似文献
19.
V. A. Kondratiev 《Journal of Mathematical Sciences》2006,135(1):2666-2674
The equations under consideration have the following structure:
where 0 < x
n < ∞, (x
1, …, x
n−1) ∈ Ω, Ω is a bounded Lipschitz domain,
is a function that is continuous and monotonic with respect to u, and all coefficients are bounded measurable functions. Asymptotic formulas are established for solutions of such equations
as x
n → + ∞; the solutions are assumed to satisfy zero Dirichlet or Neumann boundary conditions on ∂Ω. Previously, such formulas
were obtained in the case of a
ij, ai depending only on (x
1, …, x
n−1).
__________
Translated from Trudy Seminara imeni I. G. Petrovskogo, No. 25, pp. 98–111, 2005. 相似文献
20.
A. V. Demyanov 《Journal of Mathematical Sciences》2006,136(2):3706-3717
The problem of establishing necessary and sufficient conditions for l.s.c. under PDE constraints is studied for a special
class of functionals:
with respect to the convergence un → u in measure, vn ⇀ v in Lp(Ω;ℝd)
in W−1,p(Ω), and χn ⇀ χ in Lp(Ω), where χn ∈ Z:= {χ ∈ L∞(Ω): 0 ≤ χ(x) ≤ 1 for a.e. x}. Here
is a constant-rank partial differential operator. The main result is that if the characteristic cone of
has the full dimension, then the l.s.c. is equivalent to the fact that the F± are both
-quasiconvex and
for a.e. x ∈ Ω and for all u ∈ ℝd. As a corollary, we obtain several results for the functional
with respect to the same convergence. We show that this functional is l.s.c. iff
Bibliography: 14 titles.
Published in Zapiski Nauchnykh Seminarov POMI, Vol. 318, 2004, pp. 100–119. 相似文献