Decentralized Information Group

MIT Computer Science & Artificial Intelligence Laboratory (CSAIL)

Decentralized Information Group

T Berners-Lee, D.J. Weitzner, Principal Investigators

stata center

DIG Scope

Decentralized Information

Technical Scope


Mobile and pervasive computing

Policy Aware Web -- Proof Carrying Authentication

Paw architecture Departure from traditional approach to security, privacy, ownership
  • Enable flexible, decentralized approach to policy management
  • Local control (vs. global authorities)Rule-based permissions (vs. token-based access control)
  • Evaluate policies with reference to:
    • User preferences
    • Web data
    • Operating Context

Transparent Accountable Data Mining

TAMI architecture Goal: Assess applicability of usage limitation model to data mining/profiling applications.

Explore technical challenges of provable accountability in large scale, heterogeneous information systems (the Web).

Develop public policy models to enable transparency and accountable in data mining applications


Web Science

Building and understanding beneficial weblike things

Tim Berners-Lee

MIT Computer Science & Artificial Intelligence Laboratory (CSAIL)

Southampton University School of Electronics and Computer Science (ECS)

This talk

Philiosophical Engineering

Web rules



Semantic Web



SW: Everything has a URI

Don't say "colour" say <>

The relational database

A database's row, column and cell are subject, property and value.

The element of the Semantic Web

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

Semantic web includes tables,...

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

... everything

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

RDF data...

a set of circles and arrows

...merges just like that.

more circles and arrows superim

Subject and object node using same URIs

Fractal Web of concepts

The semantic web is about allowing data systems to change by evolution not revolution

Total Cost of Ontologies (TCO)

Assume :-) ontologies evenly spread across orders of magnitude; committe  size as log(community), time as comitee^2, cost shared across community.
Scale Eg Committe size Cost per ontology (weeks) My share of cost
0 Me 1 1 1
10 My team 4 16 1.6
100 Group 7 49 0.49
1000 10 100 0.10
10k Enterprise 13 169 0.017
100k Business area 16 256 0.0026
1M 19 361 0.00036
10M 22 484 0.000048
100M National, State 25 625 0.000006
1G EU, US 28 784 0.000001
10G Planet 31 961 0.000000

Total cost of 10 ontologies: 3.2 weeks. Serious project: 30 ontologies, TCO = 10 weeks.
Lesson: Do your bit. Others will do theirs.
Thank those who do working groups!

Clients of the RDF bus

New data applications can be built on top of RDF bus, for example:

db to sw

Adapting SQL Databases

Keep your existing systems running - adapt them

db to sw

Adapting XML

Remember- RDF on an HTTP server can always be virtual

db to sw

Future: Stack of expressive power

architectural layers

The Semantic Web Wave

The wave is coming...get out your surfboard

Why not instant?

Good news

When you get home

Future of Sem Web