Reasoning about numeric and symbolic time information

Many applications such as planning, scheduling and natural language processing involve managing both symbolic and numeric aspects of time. We have developed a temporal model, TemPro, based on interval algebra, to express such applications in terms of qualitative and quantitative temporal constraints. TemPro extends the interval algebra relations of Allen (1983) to handle numeric information. To solve a temporal constraint problem represented by TemPro, we have developed a method using constraint propagation at the numeric and symbolic levels. In order to deal with real time applications or those applications where a complete solution cannot be obtained, we have modified the propagation techniques so that they will be able to solve temporal problems by giving a solution with a quality depending on the time allocated for computation