Topological sequence entropy for maps of the interval

A result by Franzová and Smítal shows that a continuous map of the interval into itself is chaotic if and only if its topological sequence entropy relative to a suitable increasing sequence of nonnegative integers is positive. In the present paper we prove that for any increasing sequence of nonnegative integers there exists a chaotic continuous map with zero topological sequence entropy relative to this sequence.

     

On associated and co-recursive d-orthogonal polynomials

The associated sequence of order r for a given d-OPS (i.e. a sequence of orthogonal polynomials satisfying a (d + 1)-order recurrence relation), is again a d-OPS. In this paper we are interested in the determination of the corresponding dual sequence. The explicit form of the dual sequence of the first associated sequence and the corresponding formal Stieltjes function are given. Indeed, we construct by recurrence the dual sequence of the r-associated sequence and we give some properties of the corresponding Stieltjes function. Second, we give the definition of co-recursive polynomials of dimension d and some relations in the particular cases d = 3 and d = 4. Some properties of the dual sequence as well as of the corresponding Stieltjes functions are given.     

基于混沌序列的密钥生成新方法

设计了一种从混沌序列生成密钥的新方法.其基本原理是从混沌序列依次取若干数据构成实值序列,将其按非线性规则映射成二值序列,再用实值序列和任意指定序列分别置乱这个二值序列,被置乱后的二值序列即为所生成密钥.实验表明,在混沌密码体制研究中,这种密钥较一般序列密钥更具有独立性、均匀性和不可预测性.     

Graphic sequences with unique realization

A realization of an integer sequence means a graph which has this sequence as its degree sequence. This paper gives some characterizations of the sequences with unique labeled realization and also provides an effcient algorithm for testing if a sequence has a unique unlabeled realization.     

Score sequences of oriented graphs

We extend Landau's concept of the score structure of a tournament to that of the score sequence of an oriented graph, and give a condition for an arbitrary integer sequence to be a score sequence. The proof is by construction of a specific oriented graph Δ(S) with given score sequence S. It is shown that Δ(S) is transitive and has the minimum number of arcs among the oriented graphs with score sequence S.     

Sooner and Later Waiting Time Problems Based on a Dependent Sequence

This paper introduces a new concept: a binary sequence of order (k,r), which is an extension of a binary sequence of order k and a Markov dependent sequence. The probability functions of the sooner and later waiting time random variables are derived in the binary sequence of order (k,r). The probability generating functions of the sooner and later waiting time distributions are also obtained. Extensions of these results to binary sequence of order (g,h) are also presented.     

Prediction properties of some extrapolation methods

Convergence acceleration methods consist in the construction of a sequence converging faster than the initial sequence. Each member of the new sequence is a guess for the limit and it is computed from a restricted number of terms of the initial sequence. It is shown herein how convergence acceleration methods can be used to predict the next (unknown) term of the initial sequence instead of its limit. Particular emphasis on Aitken's △² process and the E-algorithm is placed.     

Lagrange插值和Hermite-Fejér插值在Wiener空间下的平均误差

在L_q-范数逼近的意义下,确定了基于Chebyshev多项式零点的Lagrange插值多项式列和Hermite-Fejér插值多项式列在Wiener空间下的p-平均误差的弱渐近阶.从我们的结果可以看出,当2≤q<∞,1≤p<∞时,基于第一类Chebyshev多项式零点的Lagrange插值多项式列和Hermite-Fejér插值多项式列的p-平均误差弱等价于相应的最佳逼近多项式列的p-平均误差.在信息基计算复杂性的意义下,如果可允许信息泛函为计算函数在固定点的值,那么当1≤p,q<∞时,基于第一类Chebyshev多项式零点的Lagrange插值多项式列和Hermite-Fejér插值多项式列在Wiener空间下的p-平均误差弱等价于相应的最小非自适应p-平均信息半径.     

Sur la non-universalité des couples exacts

We define the notion of triangular (Leray–Koszul) spectral sequence and show that the Jordan spectral invariants of an endomorphism form a triangular spectral sequence. We introduce the concept of a universal coupling between a spectral sequence and a triangular spectral sequence and obtain a second spectral sequence associated to a Massey exact couple. Using these ideas, we construct an example of a spectral sequence which is not derived from an exact couple. To cite this article: B. Bendiffalah, C. R. Acad. Sci. Paris, Ser. I 346 (2008).     

Interpolation between sequence transformations

Levin's sequence transformation [1] and a structurally very similar sequence transformation [4] behave quite differently in convergence acceleration and summation processes. In particular, it was found recently that Levin's transformation fails completely in the case of the strongly divergent Rayleigh-Schrödinger and renormalized perturbation expansions for the ground state energies of anharmonic oscillators, whereas the structurally very similar sequence transformation gives very good results [14,17]. For a more detailed investigation of these phenomena, a sequence transformation is constructed which — depending on a continuous parameter — is able to interpolate between Levin's transformation and the other sequence transformation. Some numerical examples, which illustrate the properties of the interpolating sequence transformation, are presented.     

<Emphasis Type="Italic">p</Emphasis>-Adic valuation of the Morgan–Voyce sequence and <Emphasis Type="Italic">p</Emphasis>-regularity

We characterize the p-adic valuation of the Morgan–Voyce sequence and its companion sequence. Further, we show that the p-adic valuation of the Morgan–Voyce sequence is a p-regular sequence and we determine its rank explicitly.     

On basic orthogonal sequences in non-archimedean metrizable locally convex spaces

We prove that any linearly independent sequence in a non-archimedean metrizable locally convex space E has a block sequence that is a basic orthogonal sequence in E.     

Finite-Order Formulation of Vinogradov's C-Spectral Sequence

The C-spectral sequence was introduced by A. M. Vinogradov in the late Seventies as a fundamental tool for the study of the algebro-geometric properties of jet spaces and differential equations. A spectral sequence arises from the contact filtration of the modules of forms on jet spaces of a fibring (or on a differential equation). In order to avoid serious technical difficulties, the order of the jet space is not fixed, i.e., computations are performed on spaces containing forms on jet spaces of any order. In this paper we show that there exists a formulation of Vinogradov's C-spectral sequence in the case of finite-order jet spaces of a fibred manifold. We compute all cohomology groups of the finite-order C-spectral sequence. We obtain a finite-order variational sequence which is shown to be naturally isomorphic with Krupka's finite-order variational sequence.     

Finite Subsequences of Shift Register Sequences

In a stream cipher a cryptogram is produced from a binary datastream by modulo-2-adding it to a keystream sequence. The securityof the system relies on the inability of an interceptor to determinethis keystream sequence. One obvious requirement for such asystem is that there should be sufficiently many possibilitiesfor the keystream sequence that the interceptor cannot possiblytry them all. In this paper we consider the likelihood of an interceptor beingable to decipher the cryptogram correctly even though he maybe trying the wrong keystream sequence. This possibility arisesbecause the length of any particular message is likely to beconsiderably shorter than the period of the keystream sequence,and thus only a comparatively small section of the keystreamsequence is used. Hence, if the interceptor tries a sequencewhich intersects (i.e. agrees) with the keystream sequence inthe appropriate positions, he will deduce the message correctly. A number of the standard methods for generating keystream sequencesuse shift registers as ‘building blocks’. So welook in considerable detail at the number of intersections (ofvarious lengths) for sequences generated by two different shiftregisters. We also show that if a keystream sequence has linearequivalence n, then the local linear equivalence of any subsequenceof length at least 2n is n. This means that if the message haslength at least 2n and the keystream sequence has linear equivalencen, then there is no other sequence of linear equivalence lessthan n+1 which can be used to decipher correctly.     

Newtonian and Schinzel sequences in a domain

A Schinzel or F sequence in a domain is such that, for every ideal I with norm q, its first q terms form a system of representatives modulo I, and a Newton or N sequence such that the first q terms serve as a test set for integer-valued polynomials of degree less than q. Strong F and strong N sequences are such that one can use any set of q consecutive terms, not only the first ones, finally a very well F ordered sequence, for short, a V.W.F sequence, is such that, for each ideal I with norm q, and each integer s,{u_sq,…,u_(s+1)q−1} is a complete set of representatives modulo I. In a quasilocal domain, V.W.F sequences and N sequences are the same, so are strong F and strong N sequences. Our main result is that a strong N sequence is a sequence which is locally a strong F sequence, and an N sequence a sequence which is locally a V.W.F. sequence. We show that, for F sequences there is a bound on the number of ideals of a given norm. In particular, a sequence is a strong F sequence if and only if it is a strong N sequence and for each prime p, there is at most one prime ideal with finite residue field of characteristic p. All results are refined to sequences of finite length.     

The Favoured Solutions of the Moment Problem

The sequence of Catalan numbers is known to be the moments of the Wigner law. A characterization of this sequence is given in terms of some determinants and the moment sequence of the q-Gaussian law is characterized in a similar fashion.     

Some new convergent sequences and inequalities of Euler's constant

In this paper, some new convergent sequences and inequalities of Euler's constant are provided. To demonstrate the superiority of our new convergent sequence over DeTemple's sequence, Vernescu's sequence and Mortici's sequences, some numerical computations are also given.     

Weakly convergent sequence coefficient in Köthe sequence spaces

In this paper, we have discussed the weakly convergent sequence coefficient in Köthe sequence spaces with as their boundedly complete basis. Using those results, we can easily calculate the weakly convergent sequence coefficient in Orlicz sequence spaces.