共查询到19条相似文献,搜索用时 265 毫秒
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本文研究了对于给定的一个三角范畴的上(下)粘合(C'',C,C"),如何由C的一个t-结构诱导C''和C"的t-结构的问题.利用左(右)t-正合函子的概念,给出了由C的一个t-结构可诱导出C''和C"的t-结构的充分条件.将粘合的一些相关结果推广到了上(下)粘合的情形. 相似文献
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Motivated by some functional models arising in fuzzy logic, when classical boolean relations between sets are generalized,
we study the functional equation S(S(x, y), T(x, y)) = S(x, y), where S is a continuous t-conorm and T is a continuous t-norm. Some interesting methods for solving this type of equations are introduced. 相似文献
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Summary We prove upper bounds on the star discrepancy of digital (t, m, 2)-nets and (t, 2)-sequences over Z2. The main tool is a decomposition lemma for digital (t, m, 2)-nets, which states that every digital (t, m, 2)-net is just the union of 2tdigitally shifted digital (0, m - t, 2)-nets. Using this result we generalize upper bounds on the star discrepancy of digital (0, m, 2) -nets and (0, 2) -sequences. 相似文献
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A. Díaz-Cano 《Journal of Pure and Applied Algebra》2001,160(2-3)
Let
be an analytic set germ of dimension 2. We study the invariant t(X0) defined as the least integer t such that any open semianalytic set germ of X0 can be written as a union of t basic open set germs. It is known that 2≤t(X0)≤3. In this note we provide a geometric criterion to determine the exact value of t(X0). 相似文献
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Olcay Arslan 《Journal of multivariate analysis》2004,89(2):420-337
In this paper, we introduce a new family of multivariate distributions as the scale mixture of the multivariate power exponential distribution introduced by Gómez et al. (Comm. Statist. Theory Methods 27(3) (1998) 589) and the inverse generalized gamma distribution. Since the resulting family includes the multivariate t distribution and the multivariate generalization of the univariate GT distribution introduced by McDonald and Newey (Econometric Theory 18 (11) (1988) 4039) we call this family as the “multivariate generalized t-distributions family”, or MGT for short. We show that this family of distributions belongs to the elliptically contoured distributions family, and investigate the properties. We give the stochastic representation of a random variable distributed as a multivariate generalized t distribution. We give the marginal distribution, the conditional distribution and the distribution of the quadratic forms. We also investigate the other properties, such as, asymmetry, kurtosis and the characteristic function. 相似文献
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This work deals with the convergence and stability of Runge–Kutta methods for systems of differential equation with piecewise continuous arguments x′(t) = Px(t)+Qx([t+1∕2]) under two cases for coe?cient matrix. First, when P and Q are complex matrices, the su?cient condition under which the analytic solution is asymptotically stable is given. It is proven that the Runge–Kutta methods are convergent with order p. Moreover, the su?cient condition under which the analytical stability region is contained in the numerical stability region is obtained. Second, when P and Q are commutable Hermitian matrices, using the theory of characteristic, the necessary and su?cient conditions under which the analytic solution and the numerical solution are asymptotically stable are presented, respectively. Furthermore, whether the Runge–Kutta methods preserve the stability of analytic solution are investigated by the theory of Padé approximation and order star. To demonstrate the theoretical results, some numerical experiments are adopted. 相似文献
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Wei‐Dong Li Zhi‐Zhong Sun Lei Zhao 《Numerical Methods for Partial Differential Equations》2007,23(2):484-498
This article is concerned with a high‐order implicit difference scheme presented by Mohanty, Jain, and George for the nonlinear hyperbolic equation utt = A(x, t)uxx + F(x, t, u, ut, ux) with Dirichlet boundary conditions. Some prior estimates of the difference solution are obtained by the energy methods. The solvability of the difference scheme is proved by the energy method and Brower's fixed point theorem. Similarly, the uniqueness, the convergence in L∞‐norm and the stability of the difference solution are obtained. A numerical example is provided to demonstrate the validity of the theoretical results. © 2006 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 23: 484–498, 2007 相似文献
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As a generalization of Haglund's statistic on Dyck paths [Conjectured statistics for the q,t-Catalan numbers, Adv. Math. 175 (2) (2003) 319–334; A positivity result in the theory of Macdonald polynomials, Proc. Nat. Acad. Sci. 98 (2001) 4313–4316], Egge et al. introduced the (q,t)-Schröder polynomial Sn,d(q,t), which evaluates to the Schröder number when q=t=1 [A Schröder generalization of Haglund's statistic on Catalan paths, Electron. J. Combin. 10 (2003) 21pp (Research Paper 16, electronic)]. In their paper, Sn,d(q,t) was conjectured to be equal to the coefficient of a hook shape on the Schur function expansion of the symmetric function en, which Haiman [Vanishing theorems and character formulas for the Hilbert scheme of points in the plane, Invent. Math. 149 (2002) 371–407] has shown to have a representation-theoretic interpretation. This conjecture was recently proved by Haglund [A proof of the q,t-Schröder conjecture, Internat. Math. Res. Not. (11) (2004) 525–560]. However, because that proof makes heavy use of symmetric function identities and plethystic machinery, the combinatorics behind it is not understood. Therefore, it is worthwhile to study it combinatorially. This paper investigates the limiting case of the (q,t)-Schröder Theorem and obtains interesting results by looking at some special cases. 相似文献
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We characterize the proper t-wise balanced designs t-(v,K,1) for t ≥ 3, λ = 1 and v ≤ 16 with at least two block sizes. While we do not examine extensions of S(3,4,16)'s, we do determine all other possible extensions of S(3,K,v)'s for v ≤ 16. One very interesting extension is an S(4, {5,6}, 17) design.©1995 John Wiley & Sons, Inc. 相似文献