Presentation on theme: "Preserving Semantics in the Web Ralph R. Swick MIT LCS & W3C"— Presentation transcript:
Preserving Semantics in the Web Ralph R. Swick MIT LCS & W3C
Semantic Web Goal Encourage humans and machines to put more specificity of meaning into the Web to enable … people to find definitions, constraints, translations machines to automate [portions of] processing preservation of intention across time & space
Annotea - Shared Annotations Human-level Annotation object described by RDF properties e.g. author date created, date modified context (specific location within annotated doc) body (the “text” of the annotation) type (e.g. Comment, Example, Explanation, …)
Model of an Annotation Instance
Annotations and Meaning Present: annotators define personal/group/ task/community annotation types using an RDF Schema each type means whatever its definer wishes it to mean, but that meaning is advertised in the Web Future: annotators define personal/…/ community properties using RDF Schema or Web Ontology Language
An Annotea Use Case: WAI WAI (Web Accessibility Initiative) Evaluation and Repair Tool ERT property definitions are created that are specialized to this task Annotations include task-specific properties identifying the WAI guidelines that a document fails to meet...
… use case: WAI ERT annotations can be created by a human expert or by an automated evaluation tool ERT annotations can be evaluated by a human (a document author) and by automated repair tools Document author can augment the annotation to communicate state to reviewers and to other tools
Schema Additions for WAI task problem Marja T17:20Z dc:date rdf:type a:created T17:20Z a:annotates dc:creator XDoc.html 4GVF1D818 a:context EARLeval OHFR427 rdf:subclass Annotation WCAG CP 1.2 “non spacer IMG with equivalent ALT -- MANUAL –” checkpoint explanation
Adding Logic and Rules Common case: “for samePropertyAs(P, R), read P is an equivalent property to R.”
Formulae semantics “This connects a document and the formula it parses to.” forAll forSome implies...
cwm - Logic Processor Forward chaining inference engine Implements some first-order logic properties for expressing rules in RDF i.e. those in
WAI proto- rule “X annotates document_D, X has type EARL:Evaluation, X has EARL:Assertor P, P has WAIcredentials WAIexpert, P asserts R, R has predicate EARL:Fails R has object TestCase_C” implies “X fails TestCase_C”
Further Information Annotea cwm Semantic Web RDF & Web Ontology Language