Toward proof exchange in the Semantic Web

Dan Connolly
Decentralized Information Group
MIT Computer Science and Artificial Intelligence Laboratory
ACL2 Seminar
September 13, 2006, Austin, TX

postscript: breadcrumbs weblog item September 16

Policy Aware Web (PAW) Project

A PAW scenario: access to girl scout event photos

Current working some PAW examples include:

The troop policy is:

  1. Photos taken at meetings of the troop can be shared with any current member of the troop.
  2. Photos taken at a jamboree can be shared with anyone in the troop or with anyone who attended the jamboree.
  3. Photos of the girls winning awards can be shared with anyone currently in the troop, or who was ever a member. These award photos can also be shared with the public if, and only if, the girl's parents allow it.

For more, see:

Transparent Accountable Datamining Initiative (TAMI) Project

A TAMI scenario:

Adverse actions premised on inferences from data where the data, while factually correct and properly in possession of the user, is used for an impermissible purpose.

TSA finds a possible name match (of a very common name) between a person in a Passenger Name Record and a person in the Terrorist Screening DataBase and properly sends the information to the FBI. The FBI arrests him for unpaid child support under the federal "Deadbeat Dad" statute. This will turn out to be impermissible because:

  1. the SORN says the purpose of collecting Passenger Name Record information is "to enhance the security of domestic air travel by identifying only those passengers who warrant further scrutiny" and
  2. the Privacy Act requires USPerson data to be used only for the purposes for which it was collected.

Semantic Web Basics

Logic, Databases, and Scale

 WebSemantic Web
Traditional Designhypertextlogic/database
-link consistency?
=viral growth

Are there parts of traditional logic and databases that, if we set them aside, will result in viral growth of the Semantic Web?

Semantic Web standards and research

semantic web topics and their status, research to standards to deployment

Berners-Lee, Jan 2003

Semantic Web Atomic Formulas

arrow tail, body and head are l are subject, property and value.

Note the relationship to HTML links, especially with the re-discovery of the rel attribute in microformats: vote-for, friend, etc..

Semantic web includes tables, trees...

Arrows can make a table, an arrow from each row to each value

Arrows can make a table, an arrow from each row to each value

... and tangly messes

Arrows can make a table, an arrow from each row to each value

RDF Terms: URIs, literals, existentials

RDFS and OWL Standards

RDF Schema (RDFS) and the Web Ontology Language (OWL) correspond to UML notions such as subclass, domain, range, cardinality, etc.

travel concepts schema


Aggregate data from friends etc, then...

table subject/property/value
  PREFIX foaf: <>
  PREFIX c: <>
  SELECT ?name, ?summary, ?when
   FROM <myFriendsBlogsData>
   WHERE { ?somebody foaf:name ?name; foaf:mbox ?mbox.
           ?event c:summary ?summary;
                  c:dtstart ?ymd;
                  c:attendee [ c:calAddress ?mbox ]
Tantek ÇelikWeb 2.02005-10-05
Norm WalshXML 20052005-11-13
Dan ConnollyW3C tech plenary2006-02-27

See SPARQL Query Language for RDF W3C Working Draft 21 July 2005

N3 Rules

@keywords is, of, a.
@prefix : <#>.

socrates a Man.
{ ?who a Man } => { ?who a Mortal }.

Reminder: we're using URIs

socrates a Man.


<#socrates> <> <#Man>.

Standard terms for idioms

We can say this much using just the RDF/RDFS standards:

socrates a Man.
Man rdfs:subClassOf Mortal.

And then we can implement the standard RDFS semantics with rules:

@prefix rdfs: <> .

{ ?X a [rdfs:subClassOf ?C] } => { ?X a ?C }.

A proof

Using web access and quoting to express policies

Expressing policies (cont)

A proof using the Vegetarian policy

Related Work