General Ontologies

The idea of creating a top level conceptual model to act as a bridge for ontologies and standards is one that has been addressed many times by those in the Artificial Intelligence and Ontology communities. In this section, I discuss some of the main top level ontologies and how they relate to the description on narrative.

The Descriptive Ontology for Linguistics and Cognitive Engineering (DOLCE) was de- veloped as part of the WonderWeb project. DOLCE was not intended as a candidate for a standard universal ontology but as a “starting point for comparing and elucidation the relationships with other future modules of the [WonderWeb] library” (Masolo et al., 2001).

Within DOLCE the relationship of a concept to time is prioritised with the primary separation of classification being between endurents, entities that are complete during

any periods of existence, and perdurents, an entity which may gain or lose parts over time but which endures as a conceptual entity despite these internal transformation. This contrasts with OntoMedia which regards all entities as potential perdurents (see Section 7.2.4.1) although any given entity may only display the the properties of an endurent.

The Cyc Knowledge Base was aimed at creating a collection of common sense rules which could then be applied and queried. One of the important aspects of Cyc was their recognition that these statements existed within a context of shared rules. This lead to the definition of contexts or microtheories which are rulesets that are true for a given set of statements so that “each context is said to have assumptions and content” (Lenat, 1998). This makes it possible to specify a context, such as a fictional universe, within which the statements are given to be true.

While it is possible to move objects between contexts by changing the statements that define them there is no way to easily describe the links between the contexts or the entities within them. This capability was considered an important aspect of describing narrative since narratives exist not only of themselves but within a tradition of other narratives. Within OntoMedia a context defines a level of comparable reality but, in conjunction with this, OntoMedia models the relationships not just within the context but also between entities within different contexts.

Further, a possible problem arises with the way that Cyc deals with potentially shifting meanings behind media such as film. “Cyc represents video as “information bearing ob- jects with propositional content””(Davis, 1994) but “this approach may break down due to the particular context-dependent and context independent semantics of video data. With video, editing and resequencing may change the given ‘propositional content’ of any ‘information bearing object”’. Davis (1994) proposes the Media Streams a “hierarchally structured semantic space of iconic primitives which are combined to form compound descriptors”, a very similar approach to OntoMedia except being focused specifically on the description of video and how the elements relate to the media more than to each other. In contrast to both these approaches, OntoMedia takes a more Jungian approach, seeing media of any type as expressing a narrative drawn from the ontological equivalent of the collective unconscious. It does this because it was felt important to recognise that there may be multiple ways of expressing a concept or narrative and that an sequence of media (either wholly or in part) may be an expression of different concepts or narratives (see Figure 2.6).

(Jenkins, 2006d) describes an example of a ‘constructed reality’ video, ‘Closer’, set within theStar Trek: Original Series universe. In ‘constructed reality’ videos, clips are taken from one or more sources and, often in conjunction with a musical audio track, are used to tell a new story rather than to illustrate a point, theme, character or relationship as occurs in most fan produced music videos. In the video that Jenkins (2006d) analyses,

Event X

Event Y

_{Event Z}

Y has­occurrence Y'

A has­occurrence A'

X has­occurrence X'

Z has­occurrence Z'

B has­occurrence B'

A'

Narrative Timeline

B'B'B'

for Context 1

X'

Narrative Timeline

Y'

Z'Z'

for Context 2

Context 2

Event B

Event A

Context 1

has­expression

has­expression

Multimedia Source 2

has­derivation

Multimedia Sources

Figure 2.6: Media Reuse and Multiple Interpretations of Source Material in OntoMedia (See Appendix F.1 for RDF)

the narrative presents a ‘what if’ scenario based around the episode ‘Amok Time’, writ- ten by Theodore Sturgeon (first aired 15 September 1967 (IMDB Staff, 2006c)). The narrative of the episode introduces the concept of ‘Pon Farr’, the Vulcan mating urge, which requires Spock to return to Vulcan and marry his fiancee or die. The fan video asks the question “What if they hadn’t made it to Vulcan on time?” and postulates a scenario in which Spock is driven to attack Kirk. As (Jenkins, 2006d) notes this harks back to a traditional theme in some of the earliest works within this fandom.

The video ends with a sequence in which we see Kirk wounded and trying to deal with the aftermath of events while Spock leaves the Enterprise in horror at his own behaviour. While each of the events containing the two characters occur at some point in the original source media they do not do so together or in the order given in the video. This can lead, in some cases, to very different implied meanings to those they had originally. For example, the scene showing a shocked and wounded Kirk. In the original context from which the clip was drawn, an episode called ‘The Enemy Within’ (first aired 6 October 1966 (IMDB Staff, 2006d)), the wounds were received when an accident causes Kirk to act abnormally and he attacks a woman on his crew, Yeoman Rand. However, in the video, the clip is proceeded by a montage showing Spock attacking Kirk thus presenting a sequence which gives a totally different impression of how the damage occurred: Kirk has gone from being the aggressor to being the victim and the injuries changed from signs of her defence to signs of his. In both cases the section of media was the same and was even used within a similar narrative (an attack on a crew mate) however the information portrayed to the watcher about Kirk by the clip is inverted.

This difference of process can also be seen in the way in which OntoMedia and Cyc model events and their temporal positioning. While the two models are very similar in that both see events as containing participants and potentially sub-events and as having both absolute and relative temporal positions (Lenat et al., 1990) the OntoMedia model divorces the temporal specifics of the event from the details of the event (see 7.2.4.1) to allow an event to have multiple instances of potentially differing temporal position or length. While, in many ways, following identical patterns to CYC, the OntoMedia ontology builds in the possibility of the description of events that go beyond the ‘common sense’ reality of human consensus knowledge (Lenat et al., 1990) into the uncommon, non-human and fantastical.

Another proposal is the Suggested Upper Merged Ontologies (SUMO) which provides a way to classify entities and bridge lower-level ontologies and was created through the combining the publicly available ontological content into a “single, comprehensive, and cohesive structure” (Niles and Pease, 2001). Niles and Pease (2001) state one of the advantage of SUMO over Cyc is that ”any distinctions of strictly philosophical interest have been removed from the ontology” thus creating a simpler knowledge base.

• Entity • Physical – Object – Process • Abstract – Attributes

The main distinction being made at this level is the differentiation between ‘Physical’ and ‘Abstract’ entities. Entities in the physical class are defined as ‘everything that has a position in space/time’ (Niles and Pease, 2001) while the abstract class covers everything else. This division is an interesting one when it comes to describing the content of a fictional world because a fictional entity does not have a position in space/time unless it is a fictionalisation of a real world object. However from the perspective of others within the abstract space in which the fictional entity resides, then it is a physical object. The OntoMedia model has a number of close similarities to the SUMO one (see Section 7.2.4.1). While OntoMedia separates events from entities at an earlier stage, it shares the high level separation of physical and abstract. However within OntoMedia this division is based on the potential of existence on space/time rather than the actuality of existence. This potentiality is also analysed on the basis of the context within which it exists. While simpler than many of the other top-level ontologies, SUMO lacks an easy way to differentiate between objects depending on their context and having differentiated them describe any existing links between them. For example: London, London as described in the books of the Sherlock Holmes mysteries and the London see in the televiseation of those books.