Supported by the National Natural Science Foundation of China under Grant No.60373081(国家自然科学基金);the Natural Science Foundation of Guangdong Province of China under Grant No.04105503(广东省自然科学基金)
Semantics on "Now" and Calculus on Temporal Relations
This paper discusses the semantics on temporal variable “Now”, that is, “Now” may express the meaning about “current”, “past” and “future” time in a valid time, and based upon this semantic analysis, the paper studies the corresponding issues for determining the temporal value of “Now” and gives a formal algebra system on the calculus of temporal relations.