We consider the problem of maximizing the revenue from selling a number of goods (or items). In this talk we will focus on approximation results and on the "menu-size" as a measure of auction complexity which affects the revenue. * All the relevant concepts will be introduced in the talk.* The talk is mostly independent of the talk given earlier this year.

Paper 1
Paper 2

Guided by several key examples, we formulate a definition of essential sequential equilibrium for multi-stage games with infinite type sets and infinite action sets, and we prove its general existence.

Paper

We discuss a new class of indices taking into account agents'preferences to coalesce.An axiomatization of these indices are presented.These indices are used to evaluate power distribution in Russian parliament in new era and in Empire period, in the Reichstag of Weimar Republic, in IMF, in Russian banks.