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In mathematics, the (linear) Peetre theorem, named after Jaak Peetre, is a result of functional analysis that gives a characterisation of differential operators in terms of their effect on generalized function spaces, and without mentioning differentiation in explicit terms. The Peetre theorem is an example of a finite order theorem in which a function or a functor, defined in a very general way, can in fact be shown to be a polynomial because of some extraneous condition or symmetry imposed upon it. This article treats two forms of the Peetre theorem. The first is the original version which, although quite useful in its own right, is actually too general for most applications. == The original Peetre theorem == Let ''M'' be a smooth manifold and let ''E'' and ''F'' be two vector bundles on ''M''. Let : be the spaces of smooth sections of ''E'' and ''F''. An ''operator'' : is a morphism of sheaves which is linear on sections such that the support of ''D'' is non-increasing: ''supp Ds'' ⊆ ''supp s'' for every smooth section ''s'' of ''E''. The original Peetre theorem asserts that, for every point ''p'' in ''M'', there is a neighborhood ''U'' of ''p'' and an integer ''k'' (depending on ''U'') such that ''D'' is a differential operator of order ''k'' over ''U''. This means that ''D'' factors through a linear mapping ''i''''D'' from the ''k''-jet of sections of ''E'' into the space of smooth sections of ''F'': : where : is the ''k''-jet operator and : is a linear mapping of vector bundles. 抄文引用元・出典: フリー百科事典『 ウィキペディア(Wikipedia)』 ■ウィキペディアで「Peetre theorem」の詳細全文を読む スポンサード リンク
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