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ma8105:2019v:lectures [2019-03-11]
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ma8105:2019v:lectures [2019-03-18]
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Linje 14: Linje 14:
 ^ 9  | Convergence and compactness in \(L^p,\ p\in(1,\infty)\).  \\ \\ Convergence and compactness in\(L^1\),  \\ Dunford-Pettis with proof, uniform integrability, de la Vallee-Poussin.  \\ \\ Convergence and compactness in \(L^\infty\)  \\ Examples.  | | p 60-65  \\ \\ p 65-75  \\ \\  | **My lecture notes** on Dunford-Pettis and equiintegrability [[http://www.math.ntnu.no/emner/MA8105/2019v/public/DunfordPettisAndEquiintegrabilityNote2019.pdf|PDF]]  \\ \\ Note that the proof of Dunford-Pettis in the notes of Holden lack the conclusion.  \\ \\ The discussion on equiintegrability can not be found in Holden, see my notes.  | ^ 9  | Convergence and compactness in \(L^p,\ p\in(1,\infty)\).  \\ \\ Convergence and compactness in\(L^1\),  \\ Dunford-Pettis with proof, uniform integrability, de la Vallee-Poussin.  \\ \\ Convergence and compactness in \(L^\infty\)  \\ Examples.  | | p 60-65  \\ \\ p 65-75  \\ \\  | **My lecture notes** on Dunford-Pettis and equiintegrability [[http://www.math.ntnu.no/emner/MA8105/2019v/public/DunfordPettisAndEquiintegrabilityNote2019.pdf|PDF]]  \\ \\ Note that the proof of Dunford-Pettis in the notes of Holden lack the conclusion.  \\ \\ The discussion on equiintegrability can not be found in Holden, see my notes.  |
 ^ 10  | Radon measures, the space \(\mathcal M\),\\ Weak * compactness in \(\mathcal M\) and the subspace \(L^1\)  \\ \\ **Sobolev Spaces** \\ Definitions, smooth approximations  | \\ \\ \\ \\ \\ \\ \\ 5  | p 75-79  \\ \\ \\ \\ \\ \\ \\ 95-97  \\ \\ | This material is partly taken from Folland: //Real Analysis// chp 7, partly from Holden.  \\ \\ **Note:** Riesz representation theorem, the space \(M\) needs be defined as the space of //finite// Radon measures.  \\ \\ **My lecture notes** on Radon measure and compactness: [[http://www.math.ntnu.no/emner/MA8105/2019v/public/LecNote04.03.2019_RadonMeasuresAndCompactness.pdf|PDF]].  \\ \\ | ^ 10  | Radon measures, the space \(\mathcal M\),\\ Weak * compactness in \(\mathcal M\) and the subspace \(L^1\)  \\ \\ **Sobolev Spaces** \\ Definitions, smooth approximations  | \\ \\ \\ \\ \\ \\ \\ 5  | p 75-79  \\ \\ \\ \\ \\ \\ \\ 95-97  \\ \\ | This material is partly taken from Folland: //Real Analysis// chp 7, partly from Holden.  \\ \\ **Note:** Riesz representation theorem, the space \(M\) needs be defined as the space of //finite// Radon measures.  \\ \\ **My lecture notes** on Radon measure and compactness: [[http://www.math.ntnu.no/emner/MA8105/2019v/public/LecNote04.03.2019_RadonMeasuresAndCompactness.pdf|PDF]].  \\ \\ |
-^ 11  | Smooth approximations (cont.) \\ straightening the boundary, extensions  \\ \\ Extensions, restrictions  |  | 97-97, 179 (App B.3)  \\ \\ \\ \\ \\ \\ 97-99  | **OBS:** //Global approx up to boundary// - the proof in Holden using straightening is not optimal and only gives \(C^1\) approximate functions. In the lectures I used the proof from //Evans: PDEs// chapter 5 that avoids straightening and give \(C^\infty\) approximations.  \\ \\ **My lecture notes** on smooth approximation up the boundary and straightening the boundary: [[http://www.math.ntnu.no/emner/MA8105/2019v/public/LecNote11.03.2019_SobolevSmApproStraightening.pdf|PDF]].  \\ \\  | +^ 11  | Smooth approximations (cont.) \\ straightening the boundary, extensions  \\ \\ Extensions, restrictions/trace   | 97-97, 179 (App B.3)  \\ \\ \\ \\ \\ \\ 97-99  | **OBS:** //Global approx up to boundary// - the proof in Holden using straightening is not optimal and only gives \(C^1\) approximate functions. In the lectures I used the proof from //Evans: PDEs// chapter 5 that avoids straightening and give \(C^\infty\) approximations.  \\ \\ **My lecture notes** on smooth approximation up the boundary and straightening the boundary: [[http://www.math.ntnu.no/emner/MA8105/2019v/public/LecNote11.03.2019_SobolevSmApproStraightening.pdf|PDF]].  \\ \\  | 
-^ 12  | Restrictions (cont),  \\ Sobolev inequalities, Gagliardo-Nirenberg-Sobolev  | | 99-102 \\ \\ 102-104  |  +^ 12  | Restrictions/trace (cont),  \\ Sobolev inequalities, Gagliardo-Nirenberg-Sobolev  \\ \\ Sobolev inequalities: Gagliardo, Poincare.  \\ \\ H\"older spaces, Morrey's inequality.  \\ \\  | | 98-102 \\ \\ 102-104  \\ \\ 105-107, 111-112  \\ \\ 110-111, 118.  | **Obs:** 3 lectures this week.  
-^ 13  | Sobolev inequalities: Gagliardo, Poincare.  \\ \\ H\"older spaces, Morrey's inequality.  \\ \\    | | 104-107, 111-112 \\ \\ 110-111, 118.  | |  +13  | General Sobolev inequalities,  \\ embedding, compactness in \(W^{1,p}\)  \\ \\  | | 116-118, 18-19, 112-114  \\ \\ | **Obs:** 1 only one lecture this week.  \\ \\ **Rellich-Kondrachov:** In the lectures I give a stronger version of this result than presented in the notes of Holden. I follow the book of Evans, and show compact embedding into Hoelder spaces \(C^{0\,\gamma}\).  \\ \\ **The proof** of the first part of Rellich-Kondarchov's compactness theorem follows from extension, Kolmogorov-Riesz compactness theorem, and interpolation in \(L^p\). This way avoids the long regularization + Arzela-Ascoli argument used in the Holden notes (and in PDE book by Evans). In fact the the regularization + Arzela-Ascoli argument is exactly the argument we used in class to proof Kolmogorov-Riesz in the first place (but the proof in the notes of Holden is slightly different).  \\ \\ **My lecture notes** from this week:  \\ \\ [[http://www.math.ntnu.no/emner/MA8105/2017v/notes/LecNote03.04.2017_GenSobolevIneq_and_RellichKondrachovCompThm.pdf|General Sobolev inequalities and Strong comactness in \(W^{1,p}\)]]  \\ \\ | 
-14  | General Sobolev inequalities,  \\ embedding, compactness in \(W^{1,p}\)  \\ \\ Compactness (cont.),  \\ Sobolev chain rule, finite differences.  \\ \\ | | 116-118, 18-19, 112-114  \\ \\ 114-116, 126, 128  \\ \\ **Rellich-Kondrachov:** In the lectures I give a stronger version of this result than presented in the notes of Holden. I follow the book of Evans, and show compact embedding into Hoelder spaces \(C^{0\,\gamma}\).  \\ \\ **The proof** of the first part of Rellich-Kondarchov's compactness theorem follows from extension, Kolmogorov-Riesz compactness theorem, and interpolation in \(L^p\). This way avoids the long regularization + Arzela-Ascoli argument used in the Holden notes (and in PDE book by Evans). In fact the the regularization + Arzela-Ascoli argument is exactly the argument we used in class to proof Kolmogorov-Riesz in the first place (but the proof in the notes of Holden is slightly different).  \\ \\ **My lecture notes** from this week:  \\ \\ [[http://www.math.ntnu.no/emner/MA8105/2017v/notes/LecNote03.04.2017_GenSobolevIneq_and_RellichKondrachovCompThm.pdf|General Sobolev inequalities and Strong comactness in \(W^{1,p}\)]]  \\ \\ [[http://www.math.ntnu.no/emner/MA8105/2017v/notes/LecNote06.04.2017_Rellich_ChainRule_and_DifferenceQuotients.pdf|Strong comactness, chain rule, and difference quotients]]  \\ \\  | +^ 14  | Compactness (cont.),  \\ Sobolev chain rule, finite differences.  \\ \\ **Application 1:** linear 2nd order elliptic PDEs, existence and uniqueness of weak solutions in \(W^{1,2}_0(\Omega)\), \(W^{2,2}(\Omega)\) interior regularity.  \\ \\ | |  114-116, 126, 128  \\ \\ \\ Evans: PDEs, parts of chp. 6.1-6.3  \\ \\ | **My lecture notes** from this week:  \\ \\ [[http://www.math.ntnu.no/emner/MA8105/2017v/notes/LecNote06.04.2017_Rellich_ChainRule_and_DifferenceQuotients.pdf|Strong comactness, chain rule, and difference quotients]]  \\ \\  | 
-^ 15  | Application: To be decided | | | | +^ 15  | **Application 2:** To be decided | | | | 
2019-04-08, Espen Robstad Jakobsen