To properly describe our NP-planning process, we need to describe how information is represented in ILEX. Domain knowledge is represented in terms of an information graph, which represents the entities of the domain, the inter-relation between these entities (called facts); and the relations between these facts (e.g., a causal relation between two facts). Figure 1 shows an abstract representation of an information graph. At present, relations between facts are not used in the NP-planner, so will not be discussed further here.
Initially, the information graph representation was developed for text planning. However, following a suggestion from Alistair Knott, we have found it useful to use it for NP-planning as well.
