The work of Elisabeth Andre, Thomas Rist, Jochen Muller, and others, at DFKI in Germany, is manifested, in one incarnation, of the PPP system (Personalized Plan-based Presenter - although one author always thinks of him as the "Playful Pointing Person") in a likable, overall-clad, virtual persona that helpfully points out aspects of commercial presentations and computer-based instruction. He has a wide variety of expressions and gestures that he uses to guide the user through tasks. The agent is embedded in Web pages and carries out presentations such as idle-time actions like breathing and tapping a foot, reactive-behaviors such as keeping current when an object that the agent is pointing to is moved by the user, and navigation acts such as walking to another screen position. (see figure 13)
The interface model has a carefully crafted appeal, designed to be used in extant products, such as, e.g., for illustrating product design, or showing real-estate, on the Web. At the same time the theoretical underpinnings of the system look carefully at the specifics of user focus and attention, and are manifested in robust hierarchical planning model after earlier work by the same researchers, and temporal reasoning models (after [Allen1983]). Furthermore, unlike for some commercial production systems, there is a a scholarly record of both the development and results of the research.
Presentations come as sequences of presentation acts which are developed in concert with a human author. While the completed ``performances'' are generally script-based, the user can interrupt the scripted sequence of events, causing the agent to initiate re-planning of the presentation under the new constraints. This all occurs under program control, wherin new script material is imported into the current environment so that the Web context remains constant (i.e., the user is not transported to another linked portion of the Web). Careful coding for efficiency allows this to run acceptably while devoting background resources to planning and recompiling on the fly.
As with most authoring systems for agent-based presentations, there are some hard, as yet unanswered, questions about how intuitive the process of creating new applications will be, and how much can be automated. To address this, DFKI is actively working on authoring applications to be used with PPP. Additionally, the hierarchical rhetorical structure used is necessarily a somewhat impoverished model of human conversation, and the current work does not seek to solve hard problems of discourse understanding, turn-taking, and so forth. Nonetheless through its on-the-fly compiling, context-sensitive reactiveness, and innovative use of planning and temporal constraint technology it supports a quite impressive set of interactions with the user.
Though the system has not been robustly tested, it is an exciting mix of old and new technology applied to a new frontier, and most particularly, like the Millenium Interactive, and Extempo work noted above, a commendable instance of commercial development that yet maintains a strong academic record. An introduction to the demos can be had at (http://www.dfki.uni-sb.de/ jmueller/ppp/persona).