时态变量“Now”语义及相应时态关系运算

Semantics on “Now” and Calculus on Temporal Relations

讨论了时态变量“Now”的基本语义,即Now不仅可以表示当前时间,还能表示过去时间和将来时间.在语义分析的基础上,讨论了带变量时态关系运算中需要解决的基本问题,即变量Now值的确定问题,研究了相应时态关系数据操作,建立了带变量时态关系代数系统.

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.