Dundee Discussion Papers in Economics 179:Activism, separation of powers and development

We consider a model of constitutional (mechanism) design with separation of powers where different institutions are assigned different tasks. In this context, we define activism as an institution extending its mechanism of decision-making into the domain of other institution’s tasks. When members of the institutions are likely to be benevolent as well as non-benevolent, such activism in a limited form reduces the cost of achieving collusion-proofness and raises welfare. Hence the value of such activism can be potentially very high in the context of developing economies. But as the fraction of non-benevolent member increases, such activism turns excessive and reduces welfare. It is argued that developing economies are likely to get caught in the excessive activism trap because of the high levels of corruption and bribery

Hypergroup Deformations of Semigroups

We view the well-known example of the dual of a countable compact hypergroup, motivated by the orbit space of p-adic integers by Dunkl and Ramirez (1975), as hypergroup deformation of the max semigroup structure on the linearly ordered set $\mathbb{Z}_+$ of the non-negative integers along the diagonal. This works as motivation for us to study hypergroups or semi convolution spaces arising from "max" semigroups or general commutative semigroups via hypergroup deformation on idempotents.Comment: 28 pages, 1 Table, This version is a truncated version with fourth section deleted from version 3, which is being developed into a separate paper. The title and abstract have been changed accordingl

Phase Diagram of Fractional Quantum Hall Effect of Composite Fermions in Multi-Component Systems

While the integer quantum Hall effect of composite fermions manifests as the prominent fractional quantum Hall effect (FQHE) of electrons, the FQHE of composite fermions produces further, more delicate states, arising from a weak residual interaction between composite fermions. We study the spin phase diagram of these states, motivated by the recent experimental observation by Liu {\em et al.} \cite{Liu14a,Liu14b} of several spin-polarization transitions at 4/5, 5/7, 6/5, 9/7, 7/9, 8/11 and 10/13 in GaAs systems. We show that the FQHE of composite fermions is much more prevalent in multicomponent systems, and consider the feasibility of such states for systems with ${\cal N}$ components for an SU(${\cal N}$) symmetric interaction. Our results apply to GaAs quantum wells, wherein electrons have two components, to AlAs quantum wells and graphene, wherein electrons have four components (two spins and two valleys), and to an H-terminated Si(111) surface, which can have six components. The aim of this article is to provide a fairly comprehensive list of possible incompressible fractional quantum Hall states of composite fermions, their SU(${\cal N}$) spin content, their energies, and their phase diagram as a function of the generalized "Zeeman" energy. We obtain results at three levels of approximation: from ground state wave functions of the composite fermion theory, from composite fermion diagonalization, and, whenever possible, from exact diagonalization. Effects of finite quantum well thickness and Landau level mixing are neglected in this study. We compare our theoretical results with the experiments of Liu {\em et al.} \cite{Liu14a,Liu14b} as well as of Yeh {\em et al.} \cite{Yeh99} for a two component system.Comment: 29 pages, 6 figure