This paper considers a sequence of discrete-time random walk markets with a single risky asset, and gives conditions for the existence of arbitrage opportunities or free lunches with vanishing risk, of the form of waiting to buy and selling the next period, with no shorting, and furthermore for...

Professor Leif Johansen (1930 – 1982) made significant contributions to a large number of fields in economics. A short survey of his contributions is presented. The main focus in the paper is on his growth – production program constituting an important part of his research. The key concepts...

We present a framework for interpretation of the empirical results of New Keynesian models of inflation dynamics. Both the rational expectations solution of the structural New Keynesian Phillips curve, NKPC, and the reduced form VAR analysis of the multivariate time series properties give...

I studied the determinants of migration from urban Ethiopia to other countries, to rural areas and to other urban areas. In general, the result differs by migration type. For international migration, wealth and network variables are found to be important. It is mainly those households who have...

The bulk of acid depositions, which have harmful effects on the environment, are caused by foreign emissions in many European countries. Therefore, if some countries emit more acids, one cannot be sure that countries that emit less will benefit from reduced acid depositions. However, numerical...

Sub-standard quality is a recurrent problem within parts of the human services - in the care for frail elderly, mentally ill, the intellectually disabled, and children in need - and within law enforcement. Service quality is of great concern to the individual, and the larger society. If so...

Piecewise deterministic control problems are problems involving stochastic disturbance of a special type. In certain situations, in an otherwise deterministic control system, it may happen that the state jumps at certain stochastic points of time. Examples are sudden oil finds, or sudden...

Social democracy, it is often said, is nice but pricey. Whatever its merits in the rich countries of Western Europe, social democracy is frequently dismissed as an infeasible model for developing countries. Based on generosity towards the poor and protection against market competition, the...

Structural forward-looking quasi-dynamic behavioural model is estimated for the Norwegian households where husband is eligible for early retirement between 1993 and 1996. Random utility approach is applied to rationalize the observed shifts between four main stages on the labour market. Specific...

Unproductive enterprises that feed on productive businesses, are rampant in developing countries. These parasitic enterprises take divergent forms, some headed by violent bandits and brutal mafia bosses, others by organized middlemen or smart political insiders. All of them seem to have the...