Completeness of the system {z^λn} in L^2[B,α0]

Let B be an unbounded domain located outside an angle domain with vertex at the origin, A ={λn}（n = 1,2,...） be a sequence of complex numbers satisfying sup ｜ arg（λn）｜ 〈 α 〈 π/2 and denote by M（∧） = {z^λ, λ ∈ ∧} the corresponding system of functions z^λ（λ∈∧）. Let α0（z） be a weight function defined on B. We obtain a completeness theorem for the system M（∧） in the Hilbert space L^2 [B, α0].     

The [n 1,n 2, ...,n s]-th reduced KP hierarchy andW 1+∞ constraints

To every partition n=n₁+n₂+...+n_s one can associate a vertex operator realization of the Lie algebras a and gl_n. Using this construction, we obtain reductions of the s-component KP hierarchy, reductions which are related to these partitions. In this way we obtain matrix KdV-type equations. We show that the following two constraints on a KP -function are equivalent: (1) is a -function of the [n₁, n₂, ..., n_s]-th reduced KP hierarchy which satisfies the string equation L_–1=0; (2) satisfies the vacuum constraints of the W₁₊ algebra.Translated from Teoreticheskaya i Matematicheskaya Fizika, Vol. 104, No. 1, pp. 32–42, July, 1995.     

关于[m,n,p_1,p_2,…,p_s]指数型群

本文给出了[m,n,p_1,p_2,…,p_s]指数型群的结构,改进了前人的结果.     

An efficient algorithm for generating all k-subsets (1 ⩽ k ⩽ m ⩽ n) of the set [1, 2,…, n] in lexicographical order

We consider the problem of generating all k-subsets (1 ? k ? m ? n) of the set [1, 2, …, n] in lexicographical order. The running time per k-subset is shown to be constant. The experimental data suggest that our algorithm is about 25% faster than the algorithm proposed by A. Nijenhuis and H. S. Wilf (“Combinatorial Algorithms,” 2nd ed., Academic Press, New York, 1978).     

Widths of classes of periodic differentiable functions in the space L 2[0, 2π]

We obtain exact values of different n-widths for classes of differentiable periodic functions in the space L ₂[0, 2π] satisfying the constraint $$ \left( {\int_0^h {\omega _m^p \left( {f^{\left( r \right)} ;t} \right)dt} } \right)^{{1 \mathord{\left/ {\vphantom {1 p}} \right. \kern-\nulldelimiterspace} p}} \leqslant \Phi \left( h \right) $$ , where 0 < h < ∞, 1/r < p ≤ 2, r ∈ ?, and ω _m (f ^(r); t) is the modulus of continuity of mth order of the derivative f ^(r)(x) ∈ L ₂[0, 2π].     

Branching Rules, Kostka–Foulkes Polynomials and q-multiplicities in Tensor Product for the Root Systems B n , C n and D n

The Kostka–Foulkes polynomials related to a root system can be defined as alternating sums running over the Weyl group associated to . By restricting these sums over the elements of the symmetric group when is of type or , we obtain again a class of Kostka–Foulkes polynomials. When is of type or there exists a duality between these polynomials and some natural -multiplicities and in tensor products [11]. In this paper we first establish identities for the which implies in particular that they can be decomposed as sums of Kostka–Foulkes polynomials with nonnegative integer coefficients. Moreover these coefficients are branching coefficients This allows us to clarify the connection between the -multiplicities and the polynomials defined by Shimozono and Zabrocki. Finally we show that and coincide up to a power of with the one dimension sum introduced by Hatayama and co-workers when all the parts of are equal to , which partially proves some conjectures of Lecouvey and Shimozono and Zabrocki.Presented by P. Littelmann.     

Zolotarev's first problem — the best approximation by polynomials of degree ≤n − 2 tox n − nσx n−1 in [−1, 1]

Chebyshev determined $$\mathop {\min }\limits_{(a)} \mathop {\max }\limits_{ - 1 \le x \le 1} |x^n + a_1 x^{n - 1} + \cdots + a_n |$$ as 2^1?n , which is attained when the polynomial is 2^1?n T _n(x), whereT _n(x) = cos(n arc cosx). Zolotarev's First Problem is to determine $$\mathop {\min }\limits_{(a)} \mathop {\max }\limits_{ - 1 \le x \le 1} |x^n - n\sigma x^{n - 1} + a_2 x^{n - 2} + \cdots + a_n |$$ as a function ofn and the parameter σ and to find the extremal polynomials. He solved this in 1878. Another discussion was given by Achieser in 1928, and another by Erdös and Szegö in 1942. The case when 0≤|σ|≤ tan²(π/2n) is quite simple, but that for |σ|> tan²(π/2n) is quite different and very complicated. We give two new versions of the proof and discuss the change in character of the solution. Both make use of the Equal Ripple Theorem.     

On the Cluster Set C [S_n/(2nφ(n))~(1/2)] in 2-type Banach Space

Ｉｎｔｈｉｓｐａｐｅｒ，ｗｅｈａｖｅｏｂｔａｉｎｅｄｔｈｅｆｏｌｌｏｗｉｎｇｔｈｅｏｒｅｍｓ．Ｔｈｅｏｒｅｍ１　Ｌｅｔφ（ｘ）ｂｅａｉｎｃｒｅａｓｉｎｇｆｕｎｃｔｉｏｎｏｎ［０，＋∞），φ（ｘ）→＋∞ａｎｄφ（ｘ）ｘｂｅｎｏ－ｉｎｃｒｅａｓｉｎｇ（Ｗｈｅｎｘｉｓｌａｒｇｅｅｎｏｕｇｈ），ａｎｄｌｅｔＢｂｅａｓｅｐａｒａｂｌｅＢａｎａｃｈｓｐａｃｅ，ＸｂｅａＢ－ｖａｌｕｅｄｒａｎｄｏｍｖａｒｉａｂｌｅ，ｉｆｉ）Ｘ∈ＷＭ２０ｉｉ）Ｘτ－ＥＸτ∈ＣＬＴ，τ＞０，ｗｈｅｒｅＸτ＝ＸＩ｛ｙＸｙ≤τ｝ｉｉ…     

On the regularity of the growth of the modulus and argument of an entire function in the metric of L p [0, 2π]

Under sufficiently general assumptions, we describe sets of entire functions f, sets of growing functions λ, and sets of complex-valued functions H from L ^p [0, 2π], p ∈ [1, + ∞], for which

Widths of classes fromL 2[0, 2π] and minimization of exact constants in Jackson-type inequalities

The problem of minimizing the constant in Jackson-type inequalities with respect to all subspaces of dimensionN, i.e., with respect to the entire set of approximating subspaces of dimensionN, is solved. It is shown that the constant in question is equal to the value of different widths of classL ₂ (δ, τ, β, γ, θ). Translated fromMatematicheskie Zametki, Vol. 65, No. 6, pp. 816–820, June, 1999.     

Asymptotically optimally reliable circuits in the basis {x 1 & x 2 & x 3, x 1 ∨ x 2 ∨ x 3, \bar x_1 } for inverse faults at the inputs of elements

We prove that, in the basis {x ₁ & x ₂ & x ₃, x ₁ ∨ x ₂ ∨ x ₃, $ \bar x_1 $ }, for inverse faults at the inputs of functional elements, all Boolean functions f(x ₁, x ₂, ..., x _n ) can be realized by asymptotically optimally reliable circuits operating with unreliability asymptotically (as ? → 0) equal to: ? ₃ for the constants 0 and 1, ? for the functions $ \bar x_i $ , and 3? for f(x ₁, x ₂, ..., x _n ) ≠ 0, 1, $ \bar x_i $ , x _i , where ? is the error probability at each input of the functional element and i = 1, ..., n. The functions xi, i = 1, ..., n, can be realized absolutely reliably. The complexity of asymptotically optimally reliable circuits is equal in order to the complexity of minimal circuits constructed only from reliable elements.     

The best quadrature formula based on Hermite information for the class KW~2[a,b]

The best quadrature formula has been found in the following sense:for afunction whose norm of the second derivative is bounded by a given constant and thebest quadrature formula for the approximate evaluation of integration of that function canminimize the worst possible error if the values of the function and its derivative at certainnodes are known.The best interpolation formula used to get the quadrature formula aboveis also found.Moreover,we compare the best quadrature formula with the open compoundcorrected trapezoidal formula by theoretical analysis and stochastic experiments.     

P-stable andP[α, β]-stable integration/interpolation methods in the solution of retarded differential-difference equations

The equationu(t)=pu(t)+qu(t-) is presented as an archetype (scalar) equation for assessing the quality of integrator/interpolator pairs used to solve retarded differential-difference equations. The relationships ofP-stability andP[, ]-stability, defined with respect to this archetype equation, to stability and order of multistep integrators and to passivity and order of Lagrange interpolators are developed. Composite multistep integrators and composite Lagrange interpolators are considered as a means of obtaining high order pairs stable for all step-sizes over a large portion, if not all, of the (p, q)-domain on which the archetype equation is stable.The research reported herein was supported by grant MCS-7815396 from the National Science Foundation.     

二次函数y=ax2+bx+c在区间[m,n]上的最值问题及应用

本文以二次函数Y-ax2+bx+c在区间[m,n]上的最值问题为例从数、形、结果三方面来讨论. 　　……