Fuzzy modelling in population dynamics

The aim of this paper is to analyze the behavior of models which describe t he population dynamics taking into account the subjectivity in the state va riables or in the parameters. The models in this work have demographic and environmental fuzziness. The environmental fuzziness is presented using a l ife expectancy model where the fuzziness of parameters is considered. The d emographic fuzziness is presented using the continuous Malthus and logistic discrete models. An outstanding result in this case is the emergence of ne w fixed points and bifurcation values to the discrete logistic model with s ubjective state variables in form of fuzzy sets. An interpretation is offer ed for this fact which differs from the deterministic one. (C) 2000 Elsevie r Science B.V. All rights reserved.