Paulo S. B. A. Salles, Robert I. Muetzelfeldt, and Helen Pain
We are exploring different approaches to model qualitatively the vegetation, dynamics of Brazilian cerrado, in order to assess their suitability to provide the domain-specific knowledge in tutoring systems. Two formalisms, the System of Interpretation of Measurements, Analysis and Observations (SIMAO) and the Qualitative Process Theory (QPT), are compared here in two aspects: capacity for making predictions about the behaviour of a plant population, and the generation of explanations from encoded knowledge. Both SIMAO and QPT-based models can produce similar predictions to those obtained with a numerical model of the same problem. S1MAO provides a useful qualitative algebra to make calculations with heterogeneous variables. However it is not possible to incorporate descriptions of the ecological components nor do dynamic simulations with the SIMAO-based model. On the other hand, QPT allows the encoding of qualitative knowledge and building more detailed models, but does not provide a qualitative algebra for combining empirical values of variables. Both SIMAO and QPT permit the generation of system-based explanations, whereas QPT might be more recommended to generate domain-based explanations. We also discuss the role of different organisational levels and scales of space and time in explaining the behaviour of ecological systems. A combined approach could be advantageous in building tutoring systems.