共查询到20条相似文献,搜索用时 328 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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Vladimir Shchigolev 《Journal of Algebra》2009,321(5):1453-1462
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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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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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A complex C is called Gorenstein injective if there exists an exact sequence of complexes such that each is injective, and the sequence remains exact when is applied to it for any injective complex E. We show that over a left Noetherian ring R, a complex C of left R-modules is Gorenstein injective if and only if is Gorenstein injective in R-Mod for all . Also Gorenstein injective dimensions of complexes are considered. 相似文献
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Paolo Boggiatto Carmen Fernández Antonio Galbis 《Applied and Computational Harmonic Analysis》2017,42(1):65-87
Inspired by results of Kim and Ron, given a Gabor frame in , we determine a non-countable generalized frame for the non-separable space of the Besicovic almost periodic functions. Gabor type frames for suitable separable subspaces of are constructed. We show furthermore that Bessel-type estimates hold for the AP norm with respect to a countable Gabor system using suitable almost periodic norms of sequences. 相似文献
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Saïd Asserda 《Comptes Rendus Mathematique》2006,342(6):393-398
Let be a complete Riemannian manifold without boundary of dimension n and V be a vector field on M such that is bounded. Suppose that outside a compact set of M, where denotes the upper eigenvalue of ?V and are non-negative decreasing functions such that . There exists positive numbers and which depend only on n and such that if h is a function defined on M with and , where , where is a sequence of M such that , then the equation has no positive solution on M. To cite this article: S. Asserda, C. R. Acad. Sci. Paris, Ser. I 342 (2006). 相似文献
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