Late commitment: virtual story characters that can frame their world

Our long-term aim is to build virtual agents that can partake together with human interactors as characters in a story, which emerges from their interactions wich each other and with the story world (the emergent narrative approach). Improvisational theatre -- as a real-life example -- suggests an extension of the current approach to emergent narrative: the event sequence of a story does not emerge based on a fixed story world setting, but the event sequence and the story world setting underlying it, emerge together. We propose a model of this idea, which we call late commitment, meaning that choices about aspects of the story world setting are delayed until they become useful for story progression. We discuss possibilities and issues concerning the use of this technique in the context of action planning and goal adoption for character agents

Contrast in concept-to-speech generation

In concept-to-speech systems, spoken output is generated on the basis of a text that has been produced by the system itself. In such systems, linguistic information from the text generation component may be exploited to achieve a higher prosodic quality of the speech output than can be obtained in a plain text-to-speech system. In this paper we discuss how information from natural language generation can be used to compute prosody in a concept-to-speech system, focusing on the automatic marking of contrastive accents on the basis of information about the preceding discourse. We discuss and compare some formal approaches to this problem and present the results of a small perception experiment that was carried out to test which discourse contexts trigger a preference for contrastive accent, and which do not. Finally, we describe a method for marking contrastive accent in a generic concept-to-speech system called D2S. In D2S, contrastive accent is assigned to generated phrases expressing different aspects of similar events. Unlike in previous approaches, there is no restriction on the kind of entities that may be considered contrastive. This is in line with the observation that, given the ‘right' context, any two items may stand in contrast to each other