The paper proves a theorem on modified Kuhn-Tucker conditions for the case where a linearly homogenous function is part of the target function. These conditions are necessary and sufficient if target function and constraints satisfy certain re-quirements. Moreover, the envelope theorem can be...

Sugden (2000) offers an answer to the question of how unrealistic models can be used to explain real-world phenomena: by considering a set of unrealistic models, one may conclude that a result common to these models also holds for a realistic model that, however, is too complex to be analyzed,...

The paper proves that the Bayesian approach to learning and expectations formation implies no propositions that could conceivably be refuted by observation. For a (non-expanding) universe infinite in time but finite at any point of time, it is shown that by a suitable choice of priors, any...

Der Aufsatz befaßt sich mit der Frage, wie Theoreme der mathematischen Ökonomie getestet werden können und welche Rolle unrealistische Annahmen bei diesen Tests spielen. Als Beispiel dienen die bekannten Theoreme der neoklassischen Außenhandelstheorie, das Faktorpreisausgleichstheorem und...

The paper considers intersectoral capital mobility in the context of investment theory. Convex costs of adjustment explain imperfect mobility of capital between sectors. Stocks of capital are endogenous; the model essentially is a twosector growth model with Keynesian investment functions. The...