共查询到20条相似文献,搜索用时 46 毫秒
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We introduce regular expression constrained sequence alignment as the problem of finding the maximum alignment score between given strings and over all alignments such that in these alignments there exists a segment where some substring of is aligned to some substring of , and both and match a given regular expression R, i.e. where is the regular language described by R. For complexity results we assume, without loss of generality, that . A motivation for the problem is that protein sequences can be aligned in a way that known motifs guide the alignments. We present an time algorithm for the regular expression constrained sequence alignment problem where , and t is the number of states of a nondeterministic finite automaton N that accepts . We use in our algorithm a nondeterministic weighted finite automaton M that we construct from N. M has states where the transition-weights are obtained from the given costs of edit operations, and state-weights correspond to optimum alignment scores we compute using the underlying dynamic programming solution for sequence alignment. If we are given a deterministic finite automaton D accepting with states then our construction creates a deterministic finite automaton with states. In this case, our algorithm takes time. Using results in faster computation than using M when . If we only want to compute the optimum score, the space required by our algorithm is ( if we use a given ). If we also want to compute an optimal alignment then our algorithm uses space ( space if we use a given ) where and are substrings of and , respectively, , and and are aligned together in the optimal alignment that we construct. We also show that our method generalizes for the case of the problem with affine gap penalties, and for finding optimal regular expression constrained local sequence alignments. 相似文献
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Applying the frequency-uniform decomposition technique, we study the Cauchy problem for derivative Ginzburg–Landau equation , where , are complex constant vectors, , . For , we show that it is uniformly global well posed for all if initial data in modulation space and Sobolev spaces () and is small enough. Moreover, we show that its solution will converge to that of the derivative Schrödinger equation in if and in or with . For , we obtain the local well-posedness results and inviscid limit with the Cauchy data in () and . 相似文献
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We study the geometric behavior for large times of the solutions of the following equation posed in the whole space , for when the initial data are nonnegative, continuous and compactly supported. We prove that, after a finite time, becomes a concave function in the space variable and converges to all orders of differentiability to a certain parabolic shape, so-called Barenblatt-type profile, which was described in Kamin et al. (1991) [20]. Extensions to more general fully nonlinear equations are considered. 相似文献
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Marc Chaperon Santiago López de Medrano José Lino Samaniego 《Comptes Rendus Mathematique》2005,340(11):827-832
Under fairly general hypotheses, we investigate by elementary methods the structure of the p-periodic orbits of a family of transformations near when and has a simple eigenvalue which is a primitive p-th root of unity. To cite this article: M. Chaperon et al., C. R. Acad. Sci. Paris, Ser. I 340 (2005). 相似文献
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《Nonlinear Analysis: Real World Applications》2007,8(4):1040-1061
We consider the following model that describes the dynamics of epidemics in homogeneous/heterogeneous populations as well as the spreading of multiple inter-related infectious diseases:Our aim is to establish criteria such that the above system has one or multiple constant-sign periodic solutions , i.e., for each , is periodic and where is fixed. Examples are also included to illustrate the results obtained. 相似文献
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A well-known cancellation problem of Zariski asks when, for two given domains (fields) and over a field k, a k-isomorphism of () and () implies a k-isomorphism of and . The main results of this article give affirmative answer to the two low-dimensional cases of this problem:1. Let K be an affine field over an algebraically closed field k of any characteristic. Suppose , then .2. Let M be a 3-dimensional affine algebraic variety over an algebraically closed field k of any characteristic. Let be the coordinate ring of M. Suppose , then , where is the field of fractions of A.In the case of zero characteristic these results were obtained by Kang in [Ming-chang Kang, A note on the birational cancellation problem, J. Pure Appl. Algebra 77 (1992) 141–154; Ming-chang Kang, The cancellation problem, J. Pure Appl. Algebra 47 (1987) 165–171]. However, the case of finite characteristic is first settled in this article, that answered the questions proposed by Kang in [Ming-chang Kang, A note on the birational cancellation problem, J. Pure Appl. Algebra 77 (1992) 141–154; Ming-chang Kang, The cancellation problem, J. Pure Appl. Algebra 47 (1987) 165–171]. 相似文献
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We study the limit, when , of the solutions of (E) in , , with , . If where satisfies to , the limit function is a solution of (E) with a single singularity at , while if , is the maximal solution of (E). We examine similar questions for equations such as with and . To cite this article: A. Shishkov, L. Véron, C. R. Acad. Sci. Paris, Ser. I 342 (2006). 相似文献
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In this Note, we give sufficient conditions for the regularity of Leray–Hopf weak solutions to the Navier–Stokes equation. We prove that, if one of three conditions (i) where and , (ii) where and , or (iii) where and , is satisfied, then the solution is regular. These conditions improve earlier results on the conditional regularity of the Navier–Stokes equations. To cite this article: I. Kukavica, M. Ziane, C. R. Acad. Sci. Paris, Ser. I 343 (2006). 相似文献
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Sarah Crown Rundell 《Journal of Combinatorial Theory, Series A》2012,119(5):1095-1109
In this paper, we study the homology of the coloring complex and the cyclic coloring complex of a complete k-uniform hypergraph. We show that the coloring complex of a complete k-uniform hypergraph is shellable, and we determine the rank of its unique nontrivial homology group in terms of its chromatic polynomial. We also show that the dimension of the homology group of the cyclic coloring complex of a complete k-uniform hypergraph is given by a binomial coefficient. Further, we discuss a complex whose r-faces consist of all ordered set partitions where none of the contain a hyperedge of the complete k-uniform hypergraph H and where . It is shown that the dimensions of the homology groups of this complex are given by binomial coefficients. As a consequence, this result gives the dimensions of the multilinear parts of the cyclic homology groups of . 相似文献
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We state and discuss a number of fundamental asymptotic properties of solutions to one-dimensional advection–diffusion equations of the form , , , assuming initial values for some . To cite this article: P. Braz e Silva, P.R. Zingano, C. R. Acad. Sci. Paris, Ser. I 342 (2006). 相似文献
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Given a polygonal path P with vertices and a real number , a path is a t-distance-preserving approximation of P if and each straight-line edge of Q approximates the distance between and along the path P within a factor of t. We present exact and approximation algorithms that compute such a path Q that minimizes k (when given t) or t (when given k). We also present some experimental results. 相似文献