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41.
We consider large finite Toeplitz matrices with symbols of the form (1– cos )p f() where p is a natural number and f is a sufficiently smooth positive function. By employing techniques based on the use of predictor polynomials, we derive exact and asymptotic formulas for the entries of the inverses of these matrices. We show in particular that asymptotically the inverse matrix mimics the Green kernel of a boundary value problem for the differential operator Submitted: June 20, 2003  相似文献   
42.
In questo articolo, si dimostra il legame fra la semi-fattorialità e la fattorialità debole nel contesto degli ordini algebrici. In particolare, si ottiene che un ordine semi-fattoriale ha il stesso numero di classi che su chiusura integrale.  相似文献   
43.
Two new triterpene glycosides of the -amyrin series, L-C 2 and L-I 2 , 27-hydroxyursolic acid 3-O--L-arabinopyranoside and its 28-O--L-rhamnopyranosyl-(14)-O--D-glucopyranosyl-(16)-O--D-glucopyranosyl ester, are isolated from leaves ofScheffleropsis angkae(Araliaceae). The structures of the glycosides are established using chemical methods and NMR techniques ( 1 H, 13 C, 13 C-APT, COSY, TOCSY, HSQC, HMBC, and ROESY).  相似文献   
44.
We present a unifying framework to establish a lower bound on the number of semidefinite-programming-based lift-and-project iterations (rank) for computing the convex hull of the feasible solutions of various combinatorial optimization problems. This framework is based on the maps which are commutative with the lift-and-project operators. Some special commutative maps were originally observed by Lovász and Schrijver and have been used usually implicitly in the previous lower-bound analyses. In this paper, we formalize the lift-and-project commutative maps and propose a general framework for lower-bound analysis, in which we can recapture many of the previous lower-bound results on the lift-and-project ranks.  相似文献   
45.
A general module containment property is proved for almost periodic linear systems of differential equations, in both finite and infinite dimensions.  相似文献   
46.
This paper studies online scheduling problems with reassignment on two identical machines. We can reassign some jobs under certain rules after all the jobs have been assigned. Three different versions are studied and optimal algorithms are proposed.  相似文献   
47.
48.
    
We verify the conjecture formulated in [36] for suspension singularities of type g(x, y, z)=f(x, y)+zn, where f is an irreducible plane curve singularity. More precisely, we prove that the modified Seiberg–Witten invariant of the link M of g, associated with the canonical spinc structure, equals −σ(F)/8, where σ(F) is the signature of the Milnor fiber of g. In order to do this, we prove general splicing formulae for the Casson–Walker invariant and for the sign-refined Reidemeister–Turaev torsion. These provide results for some cyclic covers as well. As a by-product, we compute all the relevant invariants of M in terms of the Newton pairs of f and the integer n.  相似文献   
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50.
From one‐ to two‐ and three‐dimensional MAS NMR solid‐state experiments involving 31P and 27Al, we show that the structure of microporous alumino‐phosphate AlPO4‐40 contains at least four times more sites than expected, and we attribute two types of AlIV sites. The newly described 27Al‐31P MQ‐HMQC opens new possibilities of describing details of three‐dimensional bounded networks. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   
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