Theme, subject and actor in Vietnamese and English sentences from the perspective of systemic functional grammar

Abstract

In Systemic Functional Grammar (SFG), Theme, Subject, and Actor are three distinct semantic functions, although they do not appear in isolation but in relation to other functions within the same meaning strand. The Theme serves as the point of departure for the message, the Subject guarantees the exchange of information, and the Actor is the participant - human or non-human - who performs the action in a process. In both English and Vietnamese, these three roles may coincide in simple declarative clauses but are often clearly separated in passive constructions, inverted structures, or when non-subject Themes are present.