Multiloop algebras, iterated loop algebras and extended affine Lie algebras of nullity 2

Let M(n) be the class of all multiloop algebras of finite dimensional simple Lie algebras relative to n-tuples of commuting finite order automorphisms. It is a classical result that M(n) the class of all derived algebras modulo their centres of affine Kac-Moody Lie algebras. This combined with the Peterson-Kac conjugacy theorem for affine algebras results in a classification of the algebras in M(1). In this paper, we classify the algebras in M(2), and further determine the relationship between M(2) and two other classes of Lie algebras: the class of all loop algebras of affine Lie algebras and the class of all extended affine Lie algebras of nullity 2.Fil: Allison, Bruce. University of Alberta; CanadáFil: Berman, Stephen. No especifica;Fil: Pianzola, Arturo. University of Alberta; Canadá. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Representations of a class of lattice type vertex algebras

In this paper we study the representation theory for certain ``half lattice vertex algebras.'' In particular we construct a large class of irreducible modules for these vertex algebras. We also discuss how the representation theory of these vertex algebras are related to the representation theory of some associative algebras.Comment: latex 24 page

Implications of Skill-Biased Technological Change: International Evidence

Demand for less skilled workers decreased dramatically in the US and in other developed countries over the past two decades. WE argue that pervasive skill-biased technological change, rather than increased trade with the development world, is the principal culprit. The pervasiveness of this technological change is important for two reasons. Firstly, it is an immediate and testable implication of technological change. Secondly, under standard assumptions, the more pervasive the skill-biased technological, the greater the increase in the embodied supply of less skilled workers and the greater the increase in the embodied supply if less skilled workers and the greater the increases in the embodied supply of less skilled workers and the greater the depressing effect on their relative wages through world goods prices. In contrast, in the Heckscher-Ohlin model with small open economies the skill-bias of local technological changes does not affect wages. Thus, pervasiveness deals with a major criticism of skill-biased technological as a cause. Testing the implications of pervasive, skill-biased technological change, we find strong supporting evidence. Firstly, across the OECD, most industries have increased the proportion of skilled workers employed, despite rising or stable relative wages. Secondly, increases in demand for skills were concentrated in the same manufacturing industries in different developed countries.