共查询到20条相似文献,搜索用时 62 毫秒
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Let K be a closed convex subset of a q-uniformly smooth separable Banach space, T:K→K a strictly pseudocontractive mapping, and f:K→K an L-Lispschitzian strongly pseudocontractive mapping. For any t∈(0,1), let xt be the unique fixed point of tf+(1-t)T. We prove that if T has a fixed point, then {xt} converges to a fixed point of T as t approaches to 0. 相似文献
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M. Gürdal 《Expositiones Mathematicae》2009,27(2):153-160
In the present paper we consider the Volterra integration operator V on the Wiener algebra W(D) of analytic functions on the unit disc D of the complex plane C. A complex number λ is called an extended eigenvalue of V if there exists a nonzero operator A satisfying the equation AV=λVA. We prove that the set of all extended eigenvalues of V is precisely the set C?{0}, and describe in terms of Duhamel operators and composition operators the set of corresponding extended eigenvectors of V. The similar result for some weighted shift operator on ?p spaces is also obtained. 相似文献
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We obtain a global unique continuation result for the differential inequality |(i∂t+Δ)u|?|V(x)u| in Rn+1. This is the first result on global unique continuation for the Schrödinger equation with time-independent potentials V(x) in Rn. Our method is based on a new type of Carleman estimates for the operator i∂t+Δ on Rn+1. As a corollary of the result, we also obtain a new unique continuation result for some parabolic equations. 相似文献
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We provide a number of simplified and improved separations between pairs of Resolution-with-bounded-conjunction refutation systems, Res(d), as well as their tree-like versions, Res?(d). The contradictions we use are natural combinatorial principles: the Least number principle , LNPn and an ordered variant thereof, the Induction principle , IPn. 相似文献
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Raf Cluckers Jamshid Derakhshan Eva Leenknegt Angus Macintyre 《Annals of Pure and Applied Logic》2013
We give a definition, in the ring language, of Zp inside Qp and of Fp[[t]] inside Fp((t)), which works uniformly for all p and all finite field extensions of these fields, and in many other Henselian valued fields as well. The formula can be taken existential-universal in the ring language, and in fact existential in a modification of the language of Macintyre. Furthermore, we show the negative result that in the language of rings there does not exist a uniform definition by an existential formula and neither by a universal formula for the valuation rings of all the finite extensions of a given Henselian valued field. We also show that there is no existential formula of the ring language defining Zp inside Qp uniformly for all p . For any fixed finite extension of Qp, we give an existential formula and a universal formula in the ring language which define the valuation ring. 相似文献