Four Types of Temporal Signals
Temporal signals such as prepositions in English trigger various temporal relations over events and times. In this paper, we propose to categorize such prepositional temporal signals into four types: (1) locative signals (at, in, on), (2) measure signals (for, in), (3) boundary signals (from, to, through, till), and (4) orientation signals (before, after, from). We show that each of these signal types is constrained by its own semantic restrictions. First, each of the signal types indicates a temporal entity structure either of an atomic type such as dates, periods of time, and time amounts, or of a complex type such as bounded intervals (“from dawn till dusk”) and intervals with oriented distances (“an hour after the sunset”). Second, each signal type determines the semantic type of an eventuality that it is associated with, such as state (property) and occurrence with two sub-types, process and transition (event) à la Allen (1984) and Pustejovsky (1991). In this paper, we discuss these two semantic features associated with each of the four temporal signal types in order to lay a theoretical basis for the construction or re-specification of event-related temporal semantic annotation frameworks such as ISO-TimeML (ISO 24617-1, 2012) or its variants.