We have a richness of data about numerous aspects of our activities, yet these data are only any use when we know what they are, agree upon what they are and how they relate to each other. Semantic descriptions of data, the means by which we can achieve these aims, are widely used to help exploit data in industry, academia and at home. One way of providing such meaning or semantics for data is through "ontologies", yet these ontologies can be hard to build, especially for the very people that are expert in the fields whose knowledge is being captured but who are not experienced in the specialised "modelling" field.

In the "what if...?" project we look at the problems of creating ontologies using the Web Ontology Language (OWL). With OWL logical forms, computers can deduce knowledge that is only implied within the statements made by the modeller. So any statement made by a modeller can have a dramatic effect on what is implied. These implications can be both "good" and "bad" in terms of the aims of the modeller. Consequently, a modeller is always asking themselves "what if...?" questions as they model a field of interest. Such a question might be "what happens if I say that a planet must be orbiting a star?" or "what happens if I add in this date/time ontology?".

The aim of the "what if...?" project is to build a dialogue system allowing a person building an ontology to ask such questions and get meaningful answers. This requires getting the computer to determine what the consequences of a change in the ontology would be and getting it to present these consequences in a meaningful way. To do a good job, the system will have to understand something about what the person is trying to do and what sorts of results will be most interesting to them. For this, we need to understand more about how ontologists model a domain and interact with tools; be able to model the dialogues between a human and the authoring system; achieve responsive automated reasoning that can provide the dialogue system with the information it needs to create that dialogue.

The WhatIf project is supported by the Science and Engineering Research Council from 2012 to 2015 through grants EP/J014354/1 and EP/J014176/1.