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701.
Yuan-Tsung Tsai 《代数通讯》2013,41(10):3608-3615
Let R be a domain and R[X; D] the Ore extension of R by a sequence D of derivations of R. If D has length ≥ 2, we show that the symmetric Utumi quotient ring of R[X; D] is U s (R)[X; D], where U s (R) is the symmetric Utumi quotient ring of R. Consequently, X-inner automorphisms of R[X; D] are induced by units of U s (R) and the extended centroid of R[X; D] consists of those elements α in the center of U s (R) such that δ(α) = 0 for all δ ? D. These extend the known results for free algebras. 相似文献
702.
703.
Piotr Achinger 《代数通讯》2013,41(8):2732-2748
We generalize and simplify Langer's results concerning Frobenius direct images of line bundles on quadrics, describing explicitly the decompositions of higher Frobenius push-forwards of arithmetically Cohen–Macaulay (ACM) bundles into indecomposables, with an additional emphasis on the case of characteristic two. These results are applied to check which Frobenius push-forwards of the structure sheaf are tilting. 相似文献
704.
In this article, we first decompose a cleft extension for X ? Y into two cleft extensions for X and Y respectively, where X and Y are Hopf algebras on a commutative ring R. Conversely, we introduce the concept of consistent cleft Hopf extensions and prove that one can construct a cleft extension for X ? Y by two cleft extensions for X and Y if and only if these two cleft extensions are consistent. An example is also given to show an application of our main results. 相似文献
705.
706.
Oversampling generates super-wavelets 总被引:1,自引:0,他引:1
Dorin Ervin Dutkay Palle Jorgensen 《Proceedings of the American Mathematical Society》2007,135(7):2219-2227
We show that the second oversampling theorem for affine systems generates super-wavelets. These are frames generated by an affine structure on the space .
707.
Extension results, expressed in terms of complete boundedness, leading to necessary and sufficient conditions for the solvability of power moment problems with unbounded operator data are given. As an application, necessary and sufficient conditions for the existence of selfadjoint and normal extensions for some classes of commuting tuples of unbounded linear operators are obtained. 相似文献
708.
Figen Öke 《Applied mathematics and computation》2011,218(3):956-958
Let v be a valuation of a field K, Gv its value group and kv its residue field. Let w be an extension of v to K(x1, … , xn). w is called a residual transcendental extension of v if kw/kv is a transcendental extension. In this study a residual transcendental extension w of v to K(x1, … , xn) such that transdegkw/kv = n is defined and some considerations related with this valuation are given. 相似文献
709.
Iskander Aliev 《Journal of Combinatorial Theory, Series A》2011,118(2):525-531
Given a primitive positive integer vector a, the Frobenius number F(a) is the largest integer that cannot be represented as a non-negative integral combination of the coordinates of a. We show that for large instances the order of magnitude of the expected Frobenius number is (up to a constant depending only on the dimension) given by its lower bound. 相似文献
710.
文章类似于A-上环(coring)给出T-余单子(comonad)的一些性质(这里A是代数,T是单子(monad)).首先定义了实(firm)单子等相关概念,其次研究了与Frobenius函子等价的两个命题,最后给出了与余单子可分等价的五个命题. 相似文献