A novel analysis of temporal frame-adverbials

In this paper interpretation principles for simple and complex frame-adverbial expressions are presented. Central to these principles is a distinction between p h a s e s and p e r i o d s together with the t e m p o r a l h i e rarchy , where multiple scales of time and relations can be expressed. A system, CLOCKWISE, has been implemented which interprets Swedish temporal expressions according to the principles outlined in the paper. I n t r o d u c t i o n Temporal information is expressed and conveyed in a number of ways in natural language including tense, aspect and lexical items that carry temporal information, eg. temporal adverbs. Most researchers in this field approach temporal entities in language from the perspective of tense and aspect. But there is very little in the literature on other expressions that hold temporal information, such as temporal adverbs, certain prepositional phrases and noun phrases. In most papers the meaning of a temporal adverbial such as 'next year' is merely explained as the predicate 'next year' which specifies a point or interval of time from a reference time. In objective time-modelling systems such as /Kahn & Gorry 1977/and/Bruce 1973/ temporal expressions were never analyzed in their linguistic form; instead they had to be typed in as stereotyped lists. The internal structure of temporal expressions must be investigated in order to construct grammars that can capture general features and be of use in computational applications. In the paper I will focus on temporal frame-adverbial phrases, that is, expressions that refer to a temporal period in which events are located (Cf /Bennet& Partee 1978/,/Hinrichs 1986/). I will not discuss the complex question of how tense, aspect and temporal adverbials interact (for an outline of the problems see/Ejerhed 1987D. TemPoral frame.adverbial phrases A large group of temporal expressions can be classified as frame-adverbial phrases. /Smith 1981/ categorizes temporal frame-adverbial phrases in the following way1: Deictic Clock-Calendar 2 Dependent last week, yesterday at midnight = now, this moment + next week, tomorrow + at midnight previously, before = the same time + later, afterwards 1 My use of + and is the same as Smith's forward and backward arrows. 2 In an earlier paper (Smith 1980) Smith calls this class flexible anchoring adverbials. This classification is based on the concept of anchoring, ie. a deictic is generally anchored to the time of speech (ST), a dependent is anchored to another given time in the context, and a clock calendar adverbial can anchor to either ST or to some other context-dependent time. Smith attributes a relational value to these expressions, -, = and +. These symbols stand in turn for the relational value a n t e r i o r i t y (past), s i m u l t a n e i t y (present) and p o s t e r i o r i t y (future). Frame-adverbials can syntactically occur as adverbs, noun phrases and prepositional phrases. They can be complex expressions such as (1) On Monday next week at 6 pro. where temporal information is specified on several levels and we have a combination of deictic and clock calendar expreso sions, Complex expressions have a relatively loose syntax in that the time denoted in (1) can be expressed as (2) and (3) (2) Next week on Monday at 6 pm. (3) At 6 pm next week on Monday. The issues that need considering are the following: How is the semantic well-formedness of frame-adverbial phrases determined and, if possible, what is needed to establish their temporal reference in terms of locations on the time axis.