1. Introduction to information retrieval
Discussion Class 1
Introduction to information retrieval

2. Administration
The Cornell store is temporarily out of text books.  More have been ordered from the publisher.  
The first couple of weeks of the course will be rearranged while we wait for the textbook to be delivered.

3. Discussion Classes Format: Question
Ask a member of the class to answer
Provide opportunity for others to comment
When answering:
Give your name. Make sure that the TA hears it.
Stand up
Speak clearly so that all the class can hear

4. Question 1: Types of Information System
What are the similarities and differences between
(a) information retrieval and database management systems?
(b) information retrieval and artificial intelligence systems?

5. Question 2: Recall and Precision
(a) Define the concepts "recall" and "precision"
(b) What are the strengths of these concepts in evaluating the performance of information retrieval systems?
(c) What are the weaknesses of these concepts in evaluating the performance of information retrieval systems?

6. Question 3: Regular Expressions
(a) The reading used the term "regular expression". What is a regular expression?
(b) Why might regular expressions be important in information retrieval?

7. Question 4: Documents and Queries
(a) What is a document?
(b) What is a query?
(c) What is a Boolean query?

8. Question 5: Information Retrieval Systems
A simple algorithm for information retrieval would look at the documents in a collection, one by one. For each document, the algorithm would loop through character by character looking for a substring that matches the query.
(a) If there are n documents and an average of m characters per document, what is the order of magnitude of the time to execute this algorithm?
(b) How do you develop an algorithm that is much, much faster?