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1.
Let g(x) be a monic irreducible defectless polynomial over a henselian valued field (K, v), i.e., K(θ) is a defectless extension of (K, v) for any root θ of g(x). It is known that a complete distinguished chain for θ with respect to (K, v) gives rise to several invariants associated with g(x). Recently Ron Brown studied certain invariants of defectless polynomials by introducing strict systems of polynomial extensions. In this article, the authors establish a one-to-one correspondence between strict systems of polynomial extensions and conjugacy classes of complete distinguished chains. This correspondence leads to a simple interpretation of various results proved for strict systems. The authors give new characterizations of an invariant γ g introduced by Brown. 相似文献
2.
Peter Giesl 《Journal of Approximation Theory》2008,153(2):184-211
The basin of attraction of an asymptotically stable fixed point of the discrete dynamical system given by the iteration xn+1=g(xn) can be determined through sublevel sets of a Lyapunov function. In Giesl [On the determination of the basin of attraction of discrete dynamical systems. J. Difference Equ. Appl. 13(6) (2007) 523–546] a Lyapunov function is constructed by approximating the solution of a difference equation using radial basis functions. However, the resulting Lyapunov function is non-local, i.e. it has no negative discrete orbital derivative in a neighborhood of the fixed point. In this paper we modify the construction method by using the Taylor polynomial and thus obtain a Lyapunov function with negative discrete orbital derivative both locally and globally. 相似文献
3.
Ahuva C. Shkop 《代数通讯》2013,41(10):3813-3823
In this article, I will prove that assuming Schanuel's conjecture, an exponential polynomial with algebraic coefficients can have only finitely many algebraic roots. Furthermore, this proof demonstrates that there are no unexpected algebraic roots of any such exponential polynomial. This implies a special case of Shapiro's conjecture: if p(x) and q(x) are two exponential polynomials with algebraic coefficients, each involving only one iteration of the exponential map, and they have common factors only of the form exp (g) for some exponential polynomial g, then p and q have only finitely many common zeros. 相似文献
4.
P. Catarino 《Journal of Difference Equations and Applications》2016,22(2):343-351
In this paper we consider a g – circulant, right circulant, left circulant and a special kind of a tridiagonal matrices whose entries are h(x) – Fibonacci quaternion polynomials. We present the determinant of these matrices and with the tridiagonal matrices we show that the determinant is equal to the nth term of the h(x) – Fibonacci quaternion polynomial sequences. 相似文献
5.
A new approach to group classification problems and more general investigations on transformational properties of classes
of differential equations is proposed. It is based on mappings between classes of differential equations, generated by families
of point transformations. A class of variable coefficient (1+1)-dimensional semilinear reaction–diffusion equations of the
general form f(x)u
t
=(g(x)u
x
)
x
+h(x)u
m
(m≠0,1) is studied from the symmetry point of view in the framework of the approach proposed. The singular subclass of the equations
with m=2 is singled out. The group classifications of the entire class, the singular subclass and their images are performed with
respect to both the corresponding (generalized extended) equivalence groups and all point transformations. The set of admissible
transformations of the imaged class is exhaustively described in the general case m≠2. The procedure of classification of nonclassical symmetries, which involves mappings between classes of differential equations,
is discussed. Wide families of new exact solutions are also constructed for equations from the classes under consideration
by the classical method of Lie reductions and by generation of new solutions from known ones for other equations with point
transformations of different kinds (such as additional equivalence transformations and mappings between classes of equations). 相似文献
6.
Let G be a finite group and let r∈?. An r-coloring of G is any mapping χ:G→{1,…,r}. Colorings χ and ψ are equivalent if there exists g∈G such that χ(xg?1) = ψ(x) for every x∈G. A coloring χ is symmetric if there exists g∈G such that χ(gx?1g) = χ(x) for every x∈G. Let Sr(G) denote the number of symmetric r-colorings of G and sr(G) the number of equivalence classes of symmetric r-colorings of G. We count Sr(G) and sr(G) in the case where G is the dihedral group Dn. 相似文献
7.
Sergio Blanes Fernando Casas Ander Murua 《Foundations of Computational Mathematics》2008,8(3):357-393
A comprehensive linear stability analysis of splitting methods is carried out by means of a 2×2 matrix K(x) with polynomial entries (the stability matrix) and the stability polynomial p(x) (the trace of K(x) divided by two). An algorithm is provided for determining the coefficients of all possible time-reversible splitting schemes
for a prescribed stability polynomial. It is shown that p(x) carries essentially all the information needed to construct processed splitting methods for numerically approximating the
evolution of linear systems. By conveniently selecting the stability polynomial, new integrators with processing for linear
equations are built which are orders of magnitude more efficient than other algorithms previously available.
This paper is dedicated to Arieh Iserles on the occasion of his 60th anniversary. 相似文献
8.
For a certain class of polynomial matrices A(x), we consider transformations SA(x)R(x) with invertible matrices S and R(x), i.e., the so-called semiscalarly equivalent transformations. We indicate necessary and sufficient conditions for this type of equivalence of matrices. We introduce the notion of quasidiagonal equivalence of numerical matrices. We establish the relationship between the semiscalar and quasidiagonal equivalences and the problem of matrix pairs. 相似文献
9.
An Analog Characterization of the Grzegorczyk Hierarchy 总被引:1,自引:0,他引:1
We study a restricted version of Shannon's general purpose analog computer in which we only allow the machine to solve linear differential equations. We show that if this computer is allowed to sense inequalities in a differentiable way, then it can compute exactly the elementary functions, the smallest known recursive class closed under time and space complexity. Furthermore, we show that if the machine has access to a function f(x) with a suitable growth as x goes to infinity, then it can compute functions on any given level of the Grzegorczyk hierarchy. More precisely, we show that the model contains exactly the nth level of the Grzegorczyk hierarchy if it is allowed to solve n−3 non-linear differential equations of a certain kind. Therefore, we claim that, at least in this region of the complexity hierarchy, there is a close connection between analog complexity classes, the dynamical systems that compute them, and classical sets of subrecursive functions. 相似文献
10.
L. A. Cherkas 《Differential Equations》2011,47(10):1435-1441
We study the character of the friction function f(x) and the restoring force g(x) in the Liénard system to which a quadratic system with an invariant second-order algebraic curve (an ellipse that is a limit
cycle, a hyperbola defining two separatrix cycles, or a parabola) or fourth-order algebraic curve with an oval being a limit
cycle can be reduced. Invariant curves are constructed for quadratic systems in a five-parameter canonical family, which can
readily be reduced to Liénard systems. 相似文献
11.
The structural stability of constrained polynomial differentialsystems of the form a(x, y)x'+b(x, y)y'=f(x, y), c(x, y)x'+d(x,y)y'=g(x, y), under small perturbations of the coefficientsof the polynomial functions a, b, c, d, f and g is studied.These systems differ from ordinary differential equations atimpasse points defined by adbc=0. Extensionsto this case of results for smooth constrained differentialsystems [7] and for ordinary polynomial differential systems[5] are achieved here. 1991 Mathematics Subject Classification34C35, 34D30. 相似文献
12.
An exact formula is established for the lower second order epi-derivative of a function of the form g(F(x)), where F is a smooth map from one Banach space into another and g is a convex function (generally, not everywhere finite). Unconstrained minimization of such functions typically arise as an equivalent (in one or another sense) reduction form for many important classes of constrained optimization problems. The formula is further applied to study epi-differentiability of the max-function ƒ(x) = max{ƒ(q, x):q ε Q}. 相似文献
13.
Jitsuro Sugie Kazuhisa Kita Naoto Yamaoka 《Annali di Matematica Pura ed Applicata》2002,181(3):309-337
Our concern is to solve the oscillation problem for the non-linear self-adjoint differential equation (a(t)x’)’+b(t)g(x)=0, where g(x) satisfies the signum condition xg(x)>0 if x≠0, but is not assumed to be monotone. Sufficient conditions and necessary conditions are given for all non-trivial solutions
to be oscillatory. The obtained results show that the number 1/4 is a critical value for this problem. This paper takes a
different approach from most of the previous research. Proof is given by means of phase plane analysis of systems of Liénard
type. Examples are included to illustrate the relation between our theorems and results which were given by Cecchi, Marini
and Villari.
Received: January 5, 2001?Published online: June 11, 2002 相似文献
14.
Charef Beddani 《代数通讯》2013,41(11):4671-4678
In this paper, we will show that if (R, 𝔪) is a quasi-unmixed local ring, I an 𝔪-primary ideal of R and ?𝒱(I) is the set of Rees valuations of I, then the number of minimal prime ideals in the 𝔪-adic completion of R equals exactly the number of equivalence classes on the set ?𝒱(I) under the equivalence relation ~defined by: ν1 ~ ν2 if there exist a constant c ≥ 1 such that for all x ∈ R, ν1(x) ≤ cν2(x) and ν2(x) ≤ cν1(x). 相似文献
15.
Igor Reider 《manuscripta mathematica》1988,60(2):221-233
LetX be a minimal surface of general type and M (X) the set of equivalence classes of complex structures on the differentiable manifold underlyingX; denoting byM
x the dimension of M(X) at [X], the point corresponding to the complex structure ofX we consider the problem of finding an upper bound forM
x in terms of the basic numerical invariants ofX. The main result is the Castelunovo's bound:M
xPg(X)+2q(X) for certain irregular surfaces. We also generalize the above bound to an arbitrary dimension. 相似文献
16.
Clement W.H Lam 《Journal of Combinatorial Theory, Series A》1977,22(1):43-60
In this paper, we develop methods to solve the polynomial congruence θ(x)θ(xg) ≡ d + λ(1 + x +… + xp?1) (mod xp ? 1), where p is an odd prime and θ(x) is a polynomial with nonnegative integral coefficients. Using these methods, we construct some new addition sets that are the unions of index classes for some primes p. We also establish the nonexistence of both the (95, 10, 1, 18)-addition set and the (95, 10, 1, 56)-addition set. 相似文献
17.
O.O. Vaneeva A.G. Johnpillai R.O. Popovych C. Sophocleous 《Journal of Mathematical Analysis and Applications》2007,330(2):1363-1386
A class of variable coefficient (1+1)-dimensional nonlinear reaction–diffusion equations of the general form f(x)ut=(g(x)unux)x+h(x)um is investigated. Different kinds of equivalence groups are constructed including ones with transformations which are nonlocal with respect to arbitrary elements. For the class under consideration the complete group classification is performed with respect to convenient equivalence groups (generalized extended and conditional ones) and with respect to the set of all local transformations. Usage of different equivalences and coefficient gauges plays the major role for simple and clear formulation of the final results. The corresponding set of admissible transformations is described exhaustively. Then, using the most direct method, we classify local conservation laws. Some exact solutions are constructed by the classical Lie method. 相似文献
18.
Harry Dym Jeremy M. Greene J. William Helton Scott A. McCullough 《Journal d'Analyse Mathématique》2009,108(1):19-59
Every symmetric polynomial p = p(x) = p(x
1,..., x
g
) (with real coefficients) in g noncommuting variables x
1,..., x
g
can be written as a sum and difference of squares of noncommutative polynomials:
$
(SDS) p(x) = \sum\limits_{j = 1}^{\sigma _ + } {f_j^ + (x)^T f_j^ + (x)} - \sum\limits_{\ell = 1}^{\sigma _ - } {f_\ell ^ - (x)^T f_\ell ^ - (x)} ,
$
(SDS) p(x) = \sum\limits_{j = 1}^{\sigma _ + } {f_j^ + (x)^T f_j^ + (x)} - \sum\limits_{\ell = 1}^{\sigma _ - } {f_\ell ^ - (x)^T f_\ell ^ - (x)} ,
相似文献
19.
You Ming Liu 《数学学报(英文版)》2001,17(3):501-506
Let g(x) ∈L
2(R) and ğ(ω) be the Fourier transform of g(x). Define g
mn
(x) = e
imx
g(x−2πn). In this paper we shall give a sufficient and necessary condition under which {g
mn
(x)} constitutes an orthonormal basis of L
2(R) for compactly supported g(ω) or ˘(ω).
Received March 25, 1999, Revised November 5, 1999, Accepted September 6, 2000 相似文献
20.
We establish a duality formula for the problem Minimize f(x)+g(x) for h(x)+k(x)<0 where g, k are extended-real-valued convex functions and f, h belong to the class of functions that can be written as the lower envelope of an arbitrary family of convex functions. Applications in d.c. and Lipschitzian optimization are given. 相似文献
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