natural language querying of the semantic web

June 12, 2003 AQUAINT 18 Month MeetingSan Diego CA

Natural Language Queryingof the

Semantic Web

SRI International

Information Science Institute


Beyond Single QuestionSingle Source Answers

• Most question answering systems to date have been limited to querying a single kind of source, a corpus of texts, for answers to a given question.

• Most have been limited to answering single questions with single factual answers.

• Aim: to move beyond these limits Use of multiple (semi-)structured sources Information-gathering dialogues


QUARK

• Natural language front end Gemini: Unification Grammar (CFG backbone)

• Mediated by powerful reasoning tool SNARK: Full FO Theorem Prover

• Powerful resource description and access capabilities OAA: Intelligent delegation-based middleware

• Visualization capabilities TerraVision: Terrain Viewer


Multiple Sources

• Access to multiple knowledge sources ADL Gazetteer CIA World Factbook NASA data sources TextPro IE engine


Goal: To Integrate DAML Search into QUARK

• Agent Semantic Communications Service (ASCS)

• Developed by Teknowledge.

• Searches the Web for DAML pages.

• Provides GUI for search.

• Provides inference capability aimed at broadening and relaxation of queries.


The ASCS Search Page


ASCS: A Use Case

pred: capital

arg1:

arg2: Syria

?x

Searches entireSemantic Web

Also conjunctive queries: population of capital of Syria

To find the capital of Syria, a user must input

Problem: Doesn’t support natural language input; using ASCS requires knowing some logic.

capital(?x,Syria)


How to Use ASCS in QUARK

• Questions parsed by Gemini to yield logical form.• Logical form submitted to SNARK as conjecture.• Conjecture proved in application-domain theory.• Capabilities of ASCS and other sources advertised in

theory.• ASCS provided with OAA wrapper.• Resources invoked as appropriate by procedural

attachment.• Answer, as extracted from proof.

• Presented textually• Visualization tool invoked


“Show the capitals of Islamic countries that border Iraq.”

Logical form produced by Gemini:

(and country (?x) islamic (?x) bordering-relation (?z)goal (?z, iraq) source (?z, ?x) capital-of (?u, ?x) show (?v) patient (?v, ?u))

Answer: ?v


Conjecture decomposed by SNARK

To show a country is Islamic, use the axioms in the application-domain theory:

if religions (?country, Muslim, ?percent)

and ?percent > 50

then islamic (?country)

if (SunniMuslim ?x, then Muslim ?x)

A country that is more than 50 percent Muslim is Islamic.

A SunniMuslim is a Muslim.


ASCS Reveals Basic Facts

• borders(Iraq, Syria)

borders(Iraq, Turkey), …..

• religions(Syria, SunniMuslim, 74)

religions(Syria, Christian, 10), …

• capital(Syria, Damascus)


Other Agents Reveal other Facts

• Alexandria Digital Library Gazetteer:

place-to-latlong(Damascus, capital, Syria;

33.5, 36.3)


Answer visualization by Terrain ViewerDamascus (capital),Syria; 33.5,36.3


Future Plans

• To move beyond single, one-off questions to scenario-based information-seeking dialogues.

• Scenario description presents a sketch of a situation/problem; much is left unsaid.

• To be filled out by a combination of application-domain theories and clarification/expansion dialogues.

• Ground further question-answering on the resulting situation model.

natural language querying of the semantic web

Documents