Kevin R. Payne is a full professor of mathematical analysis at the Università di Milano and a Fellow of the American Mathematical Society. He received a BA in Mathematics at Rice University and a PhD in Mathematics at Stony Brook University. He is the author of the book Comparison Principles for General Potential Theories and PDEs (Annals of Mathematics Studies 218, Princeton University Press) with Marco Cirant, Reese Harvey and Blaine Lawson.Davide Francesco Redaelli is a post-doc research associate in mathematics at the University of Rome Tor Vergata. He received a MSc in Mathematics at the University of Milan, under the supervision of Prof. Kevin R. Payne, and a PhD in Mathematics at the University of Padua, under the supervision of Prof. Marco Cirant. These Lecture Notes are an improved version of the main chapters of his Master’s Thesis.

• Part I. Semiconvex apparatus.- Chapter 1. Differentiability of convex functions.- Chapter 2. Semiconvex functions and upper contact jets.- Chapter 3. The lemmas of Jensen and Slodkowski.- Chapter 4. Semiconvex approximation of semicontinuous functions.- Part II. General potential-theoretic analysis.- Chapter 5. General potential theories.- Chapter 6. Duality and monotonicity in general potential theories.- Chapter 7. Basic tools in nonlinear potential theory.- Chapter 8. Semiconvex functions and subharmonics.- Chapter 9. Comparison principles.- Chapter 10. From Euclidean spaces to manifolds: a brief note.

Kevin R. Payne is a full professor of mathematical analysis at the Università di Milano and a Fellow of the American Mathematical Society. He received a BA in Mathematics at Rice University and a PhD in Mathematics at Stony Brook University. He is the author of the book Comparison Principles for General Potential Theories and PDEs (Annals of Mathematics Studies 218, Princeton University Press) with Marco Cirant, Reese Harvey and Blaine Lawson.Davide Francesco Redaelli is a post-doc research associate in mathematics at the University of Rome Tor Vergata. He received a MSc in Mathematics at the University of Milan, under the supervision of Prof. Kevin R. Payne, and a PhD in Mathematics at the University of Padua, under the supervision of Prof. Marco Cirant. These Lecture Notes are an improved version of the main chapters of his Master’s Thesis.

• Part I. Semiconvex apparatus.- Chapter 1. Differentiability of convex functions.- Chapter 2. Semiconvex functions and upper contact jets.- Chapter 3. The lemmas of Jensen and Slodkowski.- Chapter 4. Semiconvex approximation of semicontinuous functions.- Part II. General potential-theoretic analysis.- Chapter 5. General potential theories.- Chapter 6. Duality and monotonicity in general potential theories.- Chapter 7. Basic tools in nonlinear potential theory.- Chapter 8. Semiconvex functions and subharmonics.- Chapter 9. Comparison principles.- Chapter 10. From Euclidean spaces to manifolds: a brief note.

Kevin R. Payne is a full professor of mathematical analysis at the Università di Milano and a Fellow of the American Mathematical Society. He received a BA in Mathematics at Rice University and a PhD in Mathematics at Stony Brook University. He is the author of the book Comparison Principles for General Potential Theories and PDEs (Annals of Mathematics Studies 218, Princeton University Press) with Marco Cirant, Reese Harvey and Blaine Lawson.Davide Francesco Redaelli is a post-doc research associate in mathematics at the University of Rome Tor Vergata. He received a MSc in Mathematics at the University of Milan, under the supervision of Prof. Kevin R. Payne, and a PhD in Mathematics at the University of Padua, under the supervision of Prof. Marco Cirant. These Lecture Notes are an improved version of the main chapters of his Master’s Thesis.

• Part I. Semiconvex apparatus.- Chapter 1. Differentiability of convex functions.- Chapter 2. Semiconvex functions and upper contact jets.- Chapter 3. The lemmas of Jensen and Slodkowski.- Chapter 4. Semiconvex approximation of semicontinuous functions.- Part II. General potential-theoretic analysis.- Chapter 5. General potential theories.- Chapter 6. Duality and monotonicity in general potential theories.- Chapter 7. Basic tools in nonlinear potential theory.- Chapter 8. Semiconvex functions and subharmonics.- Chapter 9. Comparison principles.- Chapter 10. From Euclidean spaces to manifolds: a brief note.