Abstract
We consider the problem of reasoning with ontologies where every axiom is associated to a context, and contexts are related through a total order. These contexts could represent, for example, a degree of trust associated to the axiom, or a level of granularity for the knowledge provided. We describe an extension of tableaux-based decision procedures into methods that compute the best-fitting context for the consequences of an ontology, and apply it to the tableaux algorithm for ALC. We also describe an execution strategy that preserves most of the standard optimizations used in modern DL reasoners.