文档介绍：LBSC 796/INFM 718R: Week 12 Question Answering
Jimmy Lin
College of Information Studies
University of Maryland
Monday, April 24, 2006
The Information Retrieval Cycle
Source
Selection
Search
Query
Selection
Ranked List
Examination
Documents
Delivery
Documents
Query
Formulation
Resource
source reselection
System discovery
Vocabulary discovery
Concept discovery
Document discovery
Question Answering
Think of
Question
Answer
Retrieval
Question
Answer
Delivery
Information Seeking Behavior
Potentially difficult or time-consuming steps of the information seeking process:
Query formulation
Query refinement
Document examination and selection
What if a system can directly satisfy information needs phrased in natural language?
Question asking is intuitive for promised query = formalized query
This is a goal of question answering…
When is QA a good idea?
Question asking is effective when…
The user knows exactly what he or she wants
The desired information is short, fact-based, and (generally) context-free
Question asking is less effective when…
The information need is vague or broad
The information request is exploratory in nature
Who discovered Oxygen?
When did Hawaii e a state?
Where is Ayer’s Rock located?
What team won the World Series in 1992?
Contrasting Information Needs
Ad hoc retrieval: find me documents “like this”
Question answering
Who discovered Oxygen?
When did Hawaii e a state?
Where is Ayer’s Rock located?
What team won the World Series in 1992?
Identify positive plishments of the Hubble telescope since it was launched in 1991.
Compile a list of mammals that are considered to be endangered, identify their habitat and, if possible, specify what threatens them.
What countries export oil?
Name . cities that have a “Shubert” theater.
Who is Aaron Copland?
What is a quasar?
“Factoid”
“List”
“Definition”
From this…
Where is Portuguese spoken?
To this…
Where is Portuguese spoken?
/
Why is this