# Lecture Notes

The lecture notes were prepared by two former students in the class. Zuoqin Wang prepared lecture notes 0 through 11 in LaTeX, and Yanir Rubinstein prepared lectures 12 through 24 in TeX. They used Professor Viaclovsky's handwritten notes in producing them.

LEC # | TOPICS | LECTURE NOTES
--- | --- | ---
0 | Course Overview Examples of Harmonic Functions Fundamental Solutions for Laplacian and Heat Operator | (PDF)
1 | Harmonic Functions and Mean Value Theorem Maximum Principle and Uniqueness Harnack Inequality Derivative Estimates for Harmonic Functions Green's Representation Formula | (PDF)
2 | Definition of Green's Function for General Domains Green's Function for a Ball The Poisson Kernel and Poisson Integral Solution of Dirichlet Problem in Balls for Continuous Boundary Data Continuous + Mean Value Property <-> Harmonic | (PDF)
3 | Weak Solutions Further Properties of Green's Functions Weyl's Lemma: Regularity of Weakly Harmonic Functions | (PDF)
4 | A Removable Singularity Theorem Laplacian in General Coordinate Systems Asymptotic Expansions | (PDF)
5 | Kelvin Transform I: Direct Computation Harmonicity at Infinity, and Decay Rates of Harmonic Functions Kelvin II: Poission Integral Formula Proof Kelvin III: Conformal Geometry Proof | (PDF)
6 | Weak Maximum Princple for Linear Elliptic Operators Uniqueness of Solutions to Dirichlet Problem A Priori C^0 Estimates for Solutions to Lu = f, c leq 0 Strong Maximum Principle | (PDF)
7 | Quasilinear Equations (Minimal Surface Equation) Fully Nonlinear Equations (Monge-Ampere Equation) Comparison Principle for Nonlinear Equations | (PDF)
8 | If Delta u in L^{infty}, then u in C^{1,alpha}, any 0 < alpha < 1 If Delta u in L^{p}, p > n, then u in C^{1,alpha}, p = n/(1 - alpha) | (PDF)
9 | If Delta u in C^{alpha}, alpha > 0, then u in C^{2} Moreover, if alpha < 1, then u in C^{2,alpha} (Proof to be completed next lecture) | (PDF)
10 | Interior C^{2,alpha} Estimate for Newtonian Potential Interior C^{2,alpha} Estimates for Poisson's Equation Boundary Estimate on Newtonian Potential: C^{2,alpha} Estimate up to the Boundary for Domain with Flat Boundary Portion | (PDF)
11 | Schwartz Reflection Reviewed Green's Function for Upper Half Space Reviewed C^{2,alpha} Boundary Estimate for Poisson's Equation for Flat Boundary Portion Global C^{2,alpha} Estimate for Poisson's Equation in a Ball for Zero Boundary Data C^{2,alpha} Regularity of Dirichlet Problem in a Ball for C^{2,alpha} Boundary Data | (PDF)
12 | Global C^{2,alpha} Solution of Poisson's Equation Delta u = f in C^{alpha}, for C^{2,alpha} Boundary Values in Balls Constant Coefficient Operators Interpolation between Hölder Norms | (PDF)
13 | Interior Schauder Estimate | (PDF)
14 | Global Schauder Estimate Banach Spaces and Contraction Mapping Principle | (PDF)
15 | Continuity Method Can Solve Dirichlet Problem for General L Provided can Solve for Laplacian Corollary: Solution of C^{2, alpha} Dirichlet Problem in Balls for General L Solution of Dirichlet Problem in C^{2,alpha} for Continuous Boundary Values, in Balls | (PDF)
16 | Elliptic Regularity: If f and Coefficients of L in C^{k,alpha}, Lu = f, then u in C^{k+2,alpha} C^{2,alpha} Regularity up to the Boundary | (PDF)
17 | C^{k,alpha} Regularity up to the Boundary Hilbert Spaces and Riesz Representation Theorem Weak Solution of Dirichlet Problem for Laplacian in W^{1,2}_0 Weak Derivatives Sobolev Spaces | (PDF)
18 | Sobolev Imbedding Theorem p < n Morrey's Inequality | (PDF)
19 | Sobolev Imbedding for p > n, Hölder Continuity Kondrachov Compactness Theorem Characterization of W^{1,p} in Terms of Difference Quotients | (PDF)
20 | Characterization of W^{1,p} in Terms of Difference Quotients (cont.) Interior W^{2,2} Estimates for W^{1,2}_0 Solutions of Lu = f in L^2 | (PDF)
21 | Interior W^{k+2,2} Estimates for Solutions of Lu = f in W^{k,2} Global (up to the Boundary) W^{k+2,2} Estimates for Solutions of Lu = f in W^{k,2} | (PDF)
22 | Weak L^2 Maximum Principle Global a priori W^{k+2,2} Estimate for Lu = f, f in W^{k,2}, c(x) leq 0 | (PDF)
23 | Cube Decomposition Marcinkiewicz Interpolation Theorem L^p Estimate for the Newtonian Potential W^{1,p} Estimate for N.P. W^{2,2} Estimate for N.P. | (PDF)
24 | W^{2,p} Estimate for N.P., 1 < p < infty W^{2,p} Estimate for Operators L with Continuous Leading Order Coefficients | (PDF)