Relativity of representations in quantum mechanics

Only the position representation is used in introductory quantum mechanics and the momentum representation is not usually presented until advanced undergraduate courses. To emphasize the relativity of the representations of the abstract formulation of quantum mechanics, two examples of representations related to the operators aX+(1-a)P and (XP+PX)/2 are presented.Comment: 10 pages, no figures, accepted in Am.J.Phy

Quantum mechanics in finite dimensional Hilbert space

The quantum mechanical formalism for position and momentum of a particle in a one dimensional cyclic lattice is constructively developed. Some mathematical features characteristic of the finite dimensional Hilbert space are compared with the infinite dimensional case. The construction of an unbiased basis for state determination is discussed.Comment: 14 pages, no figure

Endogenous growth, R & D and Labour Variety

Among the great variety of endogenous growth models, only a few have been constructed to address the question of how economic growth is related to conditions in the labour market and how growth is related to unemployment. We think that these questions are important and that the little attention paid to them represents a serious gap in the existing literature. The purpose of this paper is to go some way towards …lling this gap by developing a model which can be use to study the roles of labour market policies and institutions in determining growth.