Lecturer: E. Neher

The aim of this course is to provide the participants of Concentration period I with the necessary background from the structure theory of affine and extended affine Lie algebras.
Contents. Review of split simple finite-dimensional Lie algebras and affine Kac-Moody Lie algebras. Extended affine Lie algebras: Definition, examples, first properties. Reflection systems, in particular affine reflection systems and extended affine root systems. Lie tori: Definition, properties, examples. Relation between Lie tori and extended affine Lie algebras. Classification of Lie tori.