翻訳と辞書
Words near each other
・ Titay, Zamboanga Sibugay
・ TITC
・ Titch
・ Titch (TV series)
・ Titch Moore
・ Titche-Goettinger
・ Titche-Goettinger Building
・ Titchener
・ Titchener v British Rlys Board
・ Titchfield
・ Titchfield Abbey
・ Titchfield Canal
・ Titchfield Carnival
・ Titchfield Haven National Nature Reserve
・ Titchmarsh
Titchmarsh convolution theorem
・ Titchmarsh theorem
・ Titchmarsh, Northamptonshire
・ Titchwell
・ Titchwell Marsh
・ Titcoin
・ Titcomb
・ Titcomb Mountain
・ Titcr
・ Tite
・ Tite (Guinea-Bissau)
・ Tite AFC
・ Tite Curet Alonso
・ Tite et Bérénice
・ Tite Kubo


Dictionary Lists
翻訳と辞書 辞書検索 [ 開発暫定版 ]
スポンサード リンク

Titchmarsh convolution theorem : ウィキペディア英語版
Titchmarsh convolution theorem
The Titchmarsh convolution theorem is named after Edward Charles Titchmarsh,
a British mathematician. The theorem describes the properties of the support of the convolution of two functions.
== Titchmarsh convolution theorem ==
E.C. Titchmarsh proved the following theorem in 1926:
:If \phi\,(t) and \psi(t)\, are integrable functions, such that
::\int_^\phi(t)\psi(x-t)\,dt=0
:almost everywhere in the interval 0, then there exist \lambda\geq0 and \mu\geq0 satisfying \lambda+\mu\ge\kappa such that \phi(t)=0\, almost everywhere in (0,\lambda)\,, and \psi(t)=0\, almost everywhere in (0,\mu)\,.
This result, known as the Titchmarsh convolution theorem, could be restated in the following form:
:Let \phi,\,\psi\in L^1(\mathbb). Then \inf\mathop\,\phi\ast \psi
=\inf\mathop\,\phi+\inf\mathop\,\psi if the right-hand side is finite.
:Similarly, \sup\mathop\,\phi\ast\psi=\sup\mathop\,\phi+\sup\mathop\,\psi if the right-hand side is finite.
This theorem essentially states that the well-known inclusion
:
\,\phi\ast \psi
\subset
\mathop\,\phi
+\mathop\,\psi

is sharp at the boundary.
The higher-dimensional generalization in terms of the
convex hull of the supports was proved by
J.-L. Lions in 1951:
: ''If \phi,\,\psi\in\mathcal'(\mathbb^n), then \mathop\mathop\,\phi\ast \psi=\mathop\mathop\,\phi+\mathop\mathop\,\psi.''
Above, \mathop denotes the convex hull of the set.
\mathcal'(\mathbb^n)
denotes
the space of distributions with compact support.
The theorem lacks an elementary proof.
The original proof by Titchmarsh
is based on the Phragmén–Lindelöf principle,
Jensen's inequality,
Theorem of Carleman,
and
Theorem of Valiron.
More proofs are contained in (Theorem 4.3.3 ) (harmonic analysis style),
(Chapter VI ) (real analysis style),
and (Lecture 16 ) (complex analysis style).

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「Titchmarsh convolution theorem」の詳細全文を読む



スポンサード リンク
翻訳と辞書 : 翻訳のためのインターネットリソース

Copyright(C) kotoba.ne.jp 1997-2016. All Rights Reserved.