Math Courses

An Introduction to Geometric Measure Theory and its Applications

by Dr Eris Runa (GSSI), Dr Sara Daneri (Gran Sasso Science Institute)

Europe/Rome
Ex-ISEF/Building-Main Lecture Hall (GSSI)

Ex-ISEF/Building-Main Lecture Hall

GSSI

20
Description

The aim of Geometric Measure Theory (GMT) is to study geometric properties of functions/sets in a measure theoretic sense. Such necessity  arises in a natural way when studying minimizers of a large class of variational problems.  Due to the impossibility of showing existence of minimizers directly in a class of regular functions (either due to the formation of singularities or to the applicability of the direct method), it is necessary to enlarge the space of competitors and consider functions whose differentials are represented by measures instead of continuous functions, the so-called BV functions. Several notions of differentiability and geometric properties in BV can be defined in a measure-theoretic sense. The striking and powerful achievement of GMT is that indeed such properties, defined in a functional analytic way,  turn out to have an actual geometric counterpart, in a more classical sense. In fact, exploiting the minimality assumptions  and a set of robust techniques, one can show that for a large class of variational problems the minimizers in the BV space are actually regular functions. 
 

 
 
The main topics covered in the course will be:

 
-Direct method of the Calculus of Variations and examples;
-Covering theorems;
-Hausdorff measures;
-Rectifiable sets;
-Area and Coarea Formulas;
-The Gauss-Green Theorem and Finite Perimeter sets;
-The space BV: properties, approximation by smooth functions, compactness, structure theorem;
-The structure theorem for finite perimeter sets;
-Fine properties of BV functions (approximate continuity and approximate differentiability properties)
-Chain rule in BV
-Whitney's Extension Theorem 
-An intro to Gamma Convergence 
-Regularity of perimeter minimizers (time permitting)

 
The course also aims at being a preparation for following courses on Rigidity Estimates (Runa, Daneri) and Grain Boundaries (Spadaro).