Distributions and ultradistributions on R+d through Laguerre expansions with applications to pseudo-diferential operators with radial symbols

Abstract

<p>We study the expansions of the elements in <em>S</em>(ℝ₊^d) and <em>S</em>&#39;(ℝ₊^d) with respect to the Laguerre orthonormal basis. As a consequence, we obtain the Schwartz kernel theorem for <em>S</em>(ℝ₊^d) and <em>S</em>&#39;(ℝ₊^d). Also we give the extension theorem of Whitney type for <em>S</em>(ℝ₊^d). Next, we consider the G-type spaces i.e. the spaces <em>G</em>_{<em>&alpha;</em>}^{<em>&alpha;</em>}(ℝ₊^d), &alpha;&ge;1&nbsp; and their dual spaces which can be described as analogous to the Gelfand-Shilov spaces and their dual spaces. Actually, we show the exist-ence of the topological isomorphism between the <em>G</em>-type spaces and the subspaces of the Gelfand-Shilov spaces <em>S</em>_&alpha;/2^&alpha;/2(ℝ^d), &alpha;&ge;1&nbsp;consisting of &quot;even&quot; functions. Next, we show that the Fourier Laguerre coecients of the elements in the <em>G</em>-type spaces and their dual spaces characterize these spaces through the exponential and sub-exponentia l growth of the coecients. We provide the full topological description and the kernel theorem is proved. Also two structural theorems for the dual spaces of <em>G</em>-type spaces are obtained. Furthemore, we dene the new class of the Weyl pseudo-dierential operators with radial symbols belonging to the G-type spaces and their dual spaces. The continuity properties of this class of pseudo-dierential operators over the Gelfand-Shilov type spaces and their duals are proved. In this way the class of the Weyl pseudo-dierential operators is extended to the one with the radial symbols with the exponential and sub-exponential growth rate.</p>

<p>Proučavamo razvoje elemenata iz <em>S</em>(ℝ₊^d) i <em>S</em>&#39;(ℝ₊^d) preko Lagerove ortonormirane baze. Kao posledicu dobijamo &Scaron;varcovu teoremu o jezgru za preko Lagerove ortonormirane baze. Kao posledicu dobijamo &Scaron;varcovu teoremu o jezgru za <em>S</em>(ℝ₊^d) i <em>S</em>&#39;(ℝ₊^d). Takođe, pokazujemo i Teoremu Vitnijevog tipa za <em>S</em>(ℝ₊^d) . Zatim, posmatramo prostore G-tipa i.e. prostore <em>G</em>_&alpha;^&alpha;(ℝ^d), &alpha; &ge; 1 i njihove duale koji su analogni sa Geljfand-&Scaron;ilovim prostorima i njihovim dualima. Zapravo, pokazujemo da postoji topolo&scaron;ki izomorfizam između prostora <em>G</em>-tipa i potprostora Geljfand-&Scaron;ilovih prostora <em>S</em>_&alpha;/2^&alpha;/2(ℝ^d), &alpha; &ge; 1 koji sadrže &quot;parne&quot; funkcije. Dalje, dokazujemo da Furije Lagerovi koeficijenti elemenata iz prostora <em>G</em>-tipa i njihovih duala karakteri&scaron;u ove prostore kroz eksponencijalni i sub-eksponencijalni rast tih koeficijenata. Opisujemo topolo&scaron;ku strukturu ovih prostora i dajemo &Scaron;varcovu teoremu o jezgru. Takođe, dve strukturalne teoreme za duale prostora <em>G</em>-tipa su dobijene. Dalje, defini&scaron;emo novu klasu Vejlovih pseudo-diferencijalnih operatora sa radijalnim simbolima koji se nalaze u prostorima <em>G</em>-tipa i njihovim dualima. Pokazana je neprekidnost ove klase Vejlovih pseudo-diferencijalnih operatora na prostorima Geljfand-&Scaron;ilova i na njihovim dualima. Na ovaj način klasa Vejlovih pseudo-diferencijalnih operatora je pro&scaron;irena na radijalne simbole koji imaju eksponencijalni i sub-eksponencijalni rast.</p>