Definition:
Actor in an event who initiates and carries out the event intentionally or consciously, and who exists independently of the event.
Example:
THEY decided to go.
Agent
Definition:
Undergoer that is central to an event or state that does not have control over the way the event occurs, is not structurally changed by the event, and/or is characterized as being in a certain position or condition throughout the state.
Example:
THE BALL rolled down the hill.
Theme
Definition:
Undergoer in an event that is manipulated by an agent, and with which an intentional act is performed; it exists independently of the event. For all roles containing symmetrical participants, we assume that the ordering is non-arbitrary and may be pragmatically determined and/or related to figure-ground considerations; however, the usefulness of this distinction may be application-specific.
Example:
Jennifer baked the potatoes IN THE OVEN.
Instrument
