The Logic of Time Structures: Temporal and Nonmonotonic Features

We Imbed Into a f i rs t o rder logic a representa t ion language that combines a tempora l knowledge wi th t ime stamps in a h ierarchical fash ion . Each t ime structure contains its own chronology of events: suff ic ient in for mat ion fo r an encoding of a classical tempo ra l logic. By quant i fy ing over t ime structures, we encode a moda l logic of tempora l knowledge. In add i t ion , we show how to achieve the effect of nonmono ton ic inference, by simulat ing preferent ia l entai lment w i th in a f i rs t order f ramework .