Recognizing and understanding time-terms in communication

Time-terms are used by humans to indicate a temporal frame of reference during communication with one another. The frame of time is used to indicate whether an action or event has happened in the past, is currently taking place, or will happen in the future. These terms may specify an amount of time in the form of a time difference value, a specific time moment or time period in the form of a time concept value, and a time relative to now in the form of time adverbs. In this paper, we describe how a computer program understands time terms when they are expressed in a sentence. Understanding a time-term means to find out exactly what the term stands for when it is used. We discuss what knowledge the program needs to acquire, and describe how the program uses this knowledge to recognize the various kinds of time-terms in a given sentence. We then discuss how the program understands them by classifying time concept values and time adverbs into the categories of time period and time moment. Finally, we present how to combine time-terms into a single time period or time moment when multiple terms are presented in a sentence introduced by various prepositions, e.g., at noon on Tuesday of next week. It allows the program to use the understanding to perform simple reasoning about the relationships, such as starts before or ends after, between two given time-terms or events.