contexts. We have described a new-labeled temporal algebra, whose main elements are labeled disjunctive metric constraints, label sets associated to elemental constraints, and sets of inconsistent elemental constraints (I-L-Sets). The temporal model presented is able to integrate qualitative and metric constraints on time-points and intervals. In fact, symbolic and metric constraint between intervals can be represented by means of disjunctive metric constraints between time points and a set of I-L-Sets. The model is also able to manage (*non-binary*) logical relations among elemental constraints. The reasoning algorithms on the described model are based on the distributive property for composition over intersection in labeled constraints, and guarantee consistency and obtain a minimal TCN of disjunctive metric point-based constraints. In addition, a special type of global labeled-consistent TCN is also obtained.

Labeled constraints can be organized in a hierarchy of alternative *temporal contexts*, such that temporal reasoning processes can be performed on these contexts. Reasoning algorithms guarantee consistency in each hierarchy of contexts, maintain a minimal context-dependent TCN, and allow us to determine what constraints hold in each context or in a set of alternative contexts. Thus, we can reason on a hierarchy of context-dependent constraints on intervals, points and unary durations
(Figure 17).

These described features are useful functionalities for modeling important problems in the temporal reasoning area. However, they have not been identified in previous models. Therefore, the temporal model presented here represents a flexible framework for reasoning on complex, contextdependent, metric and qualitative constraints on time-points, intervals and unary durations.

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A path-consistent algorithm can be used as the closure process on labeled TCNs, like the typical TCA algorithm as applied by Allen (1983). This path-consistent algorithm would obtain a minimal context-dependent TCN of disjunctive metric constraints. We have proposed an *incremental* reasoning process. Thus, a minimal (and consistent) context-dependent TCN is assured at each new assertion. This incremental reasoning allows us to detect whether each new input constraint is inconsistent with the previously existing ones. This can be useful when problem constraints are not