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1.
The trace inverse functions Tr(λx~(-1)) over the finite field F_(2~n) are a class of very important Boolean functions and are used in many stream ciphers such as SFINKS,RAKAPOSHI,the simple counter stream cipher(SCSC) presented by Si W and Ding C(2012),etc.In order to evaluate the security of those ciphers in resistance to(fast) algebraic attacks,the authors need to characterize algebraic properties of Tr(λx~(-1)).However,currently only some bounds on algebraic immunity of Tr(λx~(-1)) are given in the public literature,for example,the NGG upper bound and the Bayev lower bound,etc.This paper gives the exact value of the algebraic immunity of Tr(λx~(-1)) over F_(2~n),that is,AI(Tr(λx~(-1))) =[2n~(1/2)]- 2,where n ≥ 2,A ∈ F_(2~n) and λ≠ 0,which shows that Dalai's conjecture on the algebraic immunity of Tr(λx~(-1)) is correct.What is more,the authors demonstrate some weak properties of Tr(λx~(-1)) against fast algebraic attacks.  相似文献   

2.
This paper deduces the structure of LCD negacyclic codes over the finite field Fq, where q is an odd prime power. Based on the study of q-cyclotomic cosets modulo 2 n, the authors obtain the parameters of LCD negacyclic codes of lengths n =(q+1)/2,(q~m-1)/2(q-1)and q~(t·2~τ)-1/2(q~t +1), respectively. And many optimal codes are given. Moreover, the authors research two special classes of MDS LCD negacyclic codes of length n |(q-1)/2 and n |(q+1)2, respectively.  相似文献   

3.
By constructing a Gray map, a class of constacyclic codes over ring R = R+vR is studied. Using cyclic codes and negacyclic codes of length p s over ring R, the structure of (1?2v)-constacyclic codes and dual codes of length p s over ring R are given, the Gray images of (1 ? 2v)-constacyclic codes in a particular case are also studied. It is shown that linear codes of length p s over ring R are (1?2v)-constacyclic codes if and only if their Gray images are distance-invariant cyclic codes of length 2p s over ring R.  相似文献   

4.
This paper considers two parallel machine scheduling problems,where the objectives of both problems are to minimize the makespan,and the jobs arrive over time,on two uniform machines with speeds 1 and s(s≥1),and on m identical machines,respectively.For the first problem,the authors show that the on-line LPT algorithm has a competitive ratio of(1 +5~(1/2))/2≈1.6180 and the bound is tight.Furthermore,the authors prove that the on-line LPT algorithm has the best possible competitive ratio if s≥1.8020.For the second problem,the authors present a lower bound of(15-(17)~(1/2))/8≈1.3596 on the competitive ratio of any deterministic on-line algorithm.This improves a previous result of 1.3473.  相似文献   

5.
This paper studies variational discretization for the optimal control problem governed by parabolic equations with control constraints.First of all,the authors derive a priori error estimates where |||u-U(h|||L∞(J;L2(Ω))=O(h2+k).It is much better than a priori error estimates of standard finite element and backward Euler method where |||μ-Uh|||(L∞(J;L2(Ω))=O(h+ k).Secondly,the authors obtain a posteriori error estimates of residual type.Finally,the authors present some numerical algorithms for the optimal control problem and do some numerical experiments to illustrate their theoretical results.  相似文献   

6.
This paper is devoted to the study of semi-bent functions with several parameters flexible on the finite field F2n.Boolean functions defined on F2n of the form f(r)ab(x) =Trn1(axr(2m-1))+Tr41(bx(2n-1)/5) and the form g(rs)abcd(x)=Trn1(axr(2m-1))+Tr41(bx(2n-1)/5)+Trn1(cx(2m-1)1/2+1)+Trn1(dx(2m-1)s+1) where n = 2m,m = 2(mod 4),a,c ∈ F2n,and b ∈ F(16),d ∈ F2,are investigated in constructing new classes of semi-bent functions.Some characteristic sums such as Kloosterman sums and Weil sums are employed to determine whether the above functions are semi-bent or not.  相似文献   

7.
The purpose of this paper is to present a general iterative scheme as below:
and to prove that, if {α n } and {r n } satisfy appropriate conditions, then iteration sequences {x n } and {u n } converge strongly to a common element of the set of solutions of an equilibrium problem and the set of fixed points of a nonexpansive mapping and the set of solution of a variational inequality, too. Furthermore, by using the above result, we can also obtain an iterative algorithm for solution of an optimization problem , where h(x) is a convex and lower semicontinuous functional defined on a closed convex subset C of a Hilbert space H. The results presented in this paper extend, generalize and improve the results of Combettes and Hirstoaga, Wittmann, S.Takahashi, Giuseppe Marino, Hong-Kun Xu, and some others. This research is supported by the National Natural Science Foundation of China under Grant No. 10771050.  相似文献   

8.
It has been observed in laboratory experiments that when nonlinear dispersive waves are forced periodically from one end of undisturbed stretch of the medium of propagation, the signal eventually becomes temporally periodic at each spatial point. The observation has been confirmed mathematically in the context of the damped Korteweg-de Vries (KdV) equation and the damped Benjamin-Bona-Mahony (BBM) equation. In this paper we intend to show the same results hold for the pure KdV equation (without the damping terms) posed on a finite domain. Consideration is given to the initial-boundary-value problem {ut+ux+uux+uxxx=0, u(x,0)=φ(x), 0〈x〈1, t〉0,u(0,t)=h(t), u(1,t) = 0, ux(1,t) = 0, t〉0.It is shown that if the boundary forcing h is periodic with small ampitude, then the small amplitude solution u of (*) becomes eventually time-periodic. Viewing (*) (without the initial condition) as an infinite-dimensional dynamical system in the Hilbert space L^2(0, 1), we also demonstrate that for a given periodic boundary forcing with small amplitude, the system (*) admits a (locally) unique limit cycle, or forced oscillation, which is locally exponentially stable. A list of open problems are included for the interested readers to conduct further investigations.  相似文献   

9.
This paper firstly gives some necessary conditions on one-Gray weight linear codes. And then we use these results to construct several classes of one-Gray weight linear codes over ?4+u?4(u 2 = u) with type \({16^{{k_1}}}{8^{{k_2}}}{8^{{k_3}}}{4^{{k_4}}}{4^{{k_5}}}{4^{{k_6}}}{2^{{k_7}}}{2^{{k_8}}}\) based on a distance-preserving Gray map from (?4 + u?4) n to ? 4 2n . Secondly, the authors use the similar approach to do works on two-Gray (projective) weight linear codes. Finally, some examples are given to illustrate the construction methods.  相似文献   

10.
This paper presents a new algorithm for computing the extended Hensel construction(EHC) of multivariate polynomials in main variable x and sub-variables u_1, u_2, ···, u_m over a number field K. This algorithm first constructs a set by using the resultant of two initial coprime factors w.r.t. x, and then obtains the Hensel factors by comparing the coefficients of x~i on both sides of an equation. Since the Hensel factors are polynomials of the main variable with coefficients in fraction field K(u_1, u_2, ···, u_m), the computation cost of handling rational functions can be high. Therefore,the authors use a method which multiplies resultant and removes the denominators of the rational functions. Unlike previously-developed algorithms that use interpolation functions or Gr?bner basis, the algorithm relies little on polynomial division, and avoids multiplying by different factors when removing the denominators of Hensel factors. All algorithms are implemented using Magma, a computational algebra system and experiments indicate that our algorithm is more efficient.  相似文献   

11.
Along with the rapid development of economics and enhancement of industrialization, the power demand keeps rising and frequently creates mismatch between demand and supply in electricity. This provides miscellaneous energy buy-back programs with great opportunities. Such programs, when activated, offer certain amount of financial compensations to participants for reducing their energy consumption during peak time. They aim at encouraging participants to shift their electricity usage from peak to non-peak time, and thereby release the demand pressure during peak time. This paper considers a periodic-review joint pricing and inventory decision model under an energy buy-back program over finite planning horizons, in which the compensation levels, setup cost and additive random demand function are incorporated. The objective is to maximize a manufacturer’s expected total profit. By using Veinott’s conditions, it is shown that the manufacturer’s optimal decision is a state dependent (s, S, P) policy under a peak market condition, or partly an (s, S, A, P) policy under the normal market condition.  相似文献   

12.
Elliptic PDE-constrained optimal control problems with L1-control cost (L1-EOCP) are considered. To solve L1-EOCP, the primal-dual active set (PDAS) method, which is a special semismooth Newton (SSN) method, used to be a priority. However, in general solving Newton equations is expensive. Motivated by the success of alternating direction method of multipliers (ADMM), we consider extending the ADMM to L1-EOCP. To discretize L1-EOCP, the piecewise linear finite element (FE) is considered. However, different from the finite dimensional l1-norm, the discretized L1-norm does not have a decoupled form. To overcome this difficulty, an effective approach is utilizing nodal quadrature formulas to approximately discretize the L1-norm and L2-norm. It is proved that these approximation steps will not change the order of error estimates. To solve the discretized problem, an inexact heterogeneous ADMM (ihADMM) is proposed. Different from the classical ADMM, the ihADMM adopts two different weighted inner products to define the augmented Lagrangian function in two subproblems, respectively. Benefiting from such different weighted techniques, two subproblems of ihADMM can be efficiently implemented. Furthermore, theoretical results on the global convergence as well as the iteration complexity results o(1/k) for ihADMM are given. In order to obtain more accurate solution, a two-phase strategy is also presented, in which the primal-dual active set (PDAS) method is used as a postprocessor of the ihADMM. Numerical results not only confirm error estimates, but also show that the ihADMM and the two-phase strategy are highly efficient.  相似文献   

13.
The weight hierarchy of a linear [n; k; q] code C over GF(q) is the sequence (d 1, d 2, ···, d k ) where d r is the smallest support of any r-dimensional subcode of C. “Determining all possible weight hierarchies of general linear codes” is a basic theoretical issue and has important scientific significance in communication system. However, it is impossible for q-ary linear codes of dimension k when q and k are slightly larger, then a reasonable formulation of the problem is modified as: “Determine almost all weight hierarchies of general q-ary linear codes of dimension k”. In this paper, based on the finite projective geometry method, the authors study q-ary linear codes of dimension 5 in class IV, and find new necessary conditions of their weight hierarchies, and classify their weight hierarchies into 6 subclasses. The authors also develop and improve the method of the subspace set, thus determine almost all weight hierarchies of 5-dimensional linear codes in class IV. It opens the way to determine the weight hierarchies of the rest two of 5-dimensional codes (classes III and VI), and break through the difficulties. Furthermore, the new necessary conditions show that original necessary conditions of the weight hierarchies of k-dimensional codes were not enough (not most tight nor best), so, it is important to excogitate further new necessary conditions for attacking and solving the k-dimensional problem.  相似文献   

14.
This paper considers a discrete-time Geo/G/1 queue under the Min(N,D)-policy in which the idle server resumes its service if either N customers accumulate in the system or the total backlog of the service times of the waiting customers exceeds D, whichever occurs first (Min(N,D)-policy). By using renewal process theory and total probability decomposition technique, the authors study the transient and equilibrium properties of the queue length from the beginning of the arbitrary initial state, and obtain both the recursive expression of the z-transformation of the transient queue length distribution and the recursive formula for calculating the steady state queue length at arbitrary time epoch n +. Meanwhile, the authors obtain the explicit expressions of the additional queue length distribution. Furthermore, the important relations between the steady state queue length distributions at different time epochs n -, n and n + are also reported. Finally, the authors give numerical examples to illustrate the effect of system parameters on the steady state queue length distribution, and also show from numerical results that the expressions of the steady state queue length distribution is important in the system capacity design.  相似文献   

15.
This paper addresses a dynamic lot sizing problem with bounded inventory and stockout where both no backlogging and backlogging allowed cases are considered. The stockout option means that there is outsourcing in a period only when the inventory level at that period is non-positive. The production capacity is unlimited and production cost functions are linear but with fixed charges. The problem is that of satisfying all demands in the planning horizon at minimal total cost. We show that the no backlogging case can be solved in ) O(T 2) time with general concave inventory holding and outsourcing cost functions where T is the length of the planning horizon. The complexity can be reduced to O(T) when the inventory holding cost functions are also linear and have some realistic properties, even if the outsourcing cost functions remain general concave functions. When the inventory holding and outsourcing cost functions are linear, the backlogging case can be solved in O(T 3logT) time whether the outsourcing level at each period is bounded by the sum of the demand of that period and backlogging level from previous periods, or only by the demand of that period.  相似文献   

16.
Let be the set of trees on 2k+1 vertices with nearly perfect matchings, and let be the set of trees on 2k + 2 vertices with perfect matchings. The largest Laplacian spectral radii of trees in and and the corresponding trees were given by Guo (2003). In this paper, the authors determine the second to the sixth largest Laplacian spectral radii among all trees in and give the corresponding trees. This research is supported by the National Natural Science Foundation of China under Grant No. 10331020.  相似文献   

17.
Let F=C(x1,x2,…,xe,xe+1,…,xm), where x1, x2,… , xe are differential variables, and xe+1,…,xm are shift variables. We show that a hyperexponential function, which is algebraic over F,is of form g(x1, x2, …,xm)q(x1,x2,…,xe)^1/lwe+1^xe+1…wm^xm, where g∈ F, q ∈ C(x1,x2,…,xe),t∈Z^+ and we+1,…,wm are roots of unity. Furthermore,we present an algorithm for determining whether a hyperexponential function is algebraic over F.  相似文献   

18.
A new point of view of robust statistics based on a geometrical approach is tackled in this paper. Estimation procedures are carried out from a new robust cost function based on a chaining of elementary convex norms. This chain is randomly articulated in order to treat more efficiently natural outliers in data-set. Estimated parameters are considered as random fields and each of them, named articulated estimator random field (AERF) is a manifold or stratum of a stratified space with Riemannian geometry properties. From a high level excursion set, a probability distribution model Msta is presented and a system model validation geometric criterion (SYMOVAGEC) for system model structures Msys based on Riccian scalar curvatures is proposed. Numerical results are drawn in a context of system identification.  相似文献   

19.
This paper proposes to use the blockwise empirical likelihood(EL) method to construct the confidence regions for the regression vector β in a partially linear model under negatively associated errors. It is shown that the blockwise EL ratio statistic for β is asymptotically χ~2 distributed. The result is used to obtain an EL-based confidence region for β. Results of a simulation study on the finite sample performance of the proposed confidence regions are reported.  相似文献   

20.
On the axioms of revealed preference in fuzzy consumer theory   总被引:5,自引:0,他引:5  
The revealed preference is a central subject in classical consumer theory.Authors likeSamuelson,Arrow,Richter,Sen,Uzawa and others have proposed an axiomatic setting of revealedpreference theory.Consequently revealed preference axioms WARP and SARP and congruence axioms WCA andSCA have been considered.An important theorem of Sen establishes the equivalence between these axioms provided thefamily of budgets includes all non-empty finite sets of bundles.Fuzzy consumer theory(=fuzzy choice functions)is a topic that appears in a lot of papers.Particularly,Banerjee studies in fuzzy context axioms of revealed preference and congruenceextending some results of Arrow and Sen.In this paper we modify the Banerjee definition of a fuzzy choice function(=fuzzy consumer)and we study some fuzzy versions of the axioms of revealed preference and congruence.Banerjeefuzzifies only the range of a consumer;we use a fuzzification of both the domain and the range of aconsumer.The axioms WAFRP,SAFRP,WFCA,SFCA generalize to fu  相似文献   

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