A framework for identity based on situation theory

This paper presents a computational framework for identity (initially about the culprit in a crime scene) based on Barwise's situation theory. Situations support information and can carry information about other situations. An utterance situation carries information about a described situation thanks to the constraints imposed by natural language. We are concerned with utterance situations (which we call an id-situation or id-case) in which identity judgments are made about the culprit in a crime scene, which is the corresponding described situation. The id-situation and crime scene along with various resource situations make up a case in the legal sense. Resource situations include such things as where a fingerprint was filed and where one took a facial image used to train a classifier. In an investigation, there may be several coordinated id-cases that use different means in search of the same judgment. We utilize Semantic Web standards to express cases in our framework. We have developed Web Ontology Language (OWL) ontologies to provide concepts and principled vocabularies for encoding our scenarios in Resource Description Framework (RDF), and we present an example of a SPARQL Protocol and RDF Query Language (SPARQL) query of one of our encodings that spans situations. To follow how evidence supports hypotheses on the identity of the culprit in a crime scene, we use Dempster-Shafer theory, which provides numerical values for evidence-based confidence one should have in our identities. We tightly integrate it with our ontologies by having the representation of a case per our ontologies present a network containing situations and stitched together by objects; evidence "flows" along this network, diminishing and combining. We review the modifications of Dempster-Shafer theory required when one goes from a closed world assumption, where the number of suspects or candidates is bounded, to an open world assumption, where there is an unbounded number of suspects or candidates. We review our plans regarding equational reasoning based on identities established in our id-cases, and we review the related issues regarding the meanings of Universal Resource Identifiers (URIs). URIs are the fundamental denoting expressions ("names") on the Semantic Web, and an account of identity using Semantic-Web resources must be clear on what is required for a URI to denote something. On the pre-Semantic Web, a URI just identifies the web-page its protocol accesses, but on the Semantic Web, URIs are used to identify all resources, causing confusion between a thing and a page about it. We review three positions on the meanings of denoting expression and note that they apply to URIs as used in our encodings of scenarios.