Unsolved Problems in Group Theory. The Kourovka Notebook

This is a collection of open problems in group theory proposed by hundreds of mathematicians from all over the world. It has been published every 2-4 years in Novosibirsk since 1965. This is the 19th edition, which contains 111 new problems and a number of comments on about 1000 problems from the previous editions.Comment: A few new solutions and references have been added or update

Mechanics and Equilibrium Geometry of Black Holes, Membranes, and Strings

This course is designed to give a mathematically coherent introduction to the classical thory of black holes and also of strings and membranes (which are like the horizon of a black hole in being examples of physical systems based on a dynamically evolving world sheet) giving particular attention given to the study of the geometry of their equilibrium states.Comment: 93 page latex file (with typo corrections and redrafted C.P. diagrams) of contribution to BLACK HOLE PHYSICS (NATO ASI C364) ed. V. de Sabbata, Z. Zhang (Kluwer, Dordrecht, 1992) 283-35