Boolean Retrieval System

A simple Java implementation of a Boolean Retrieval System. This is the Project #1 of the Information Retrieval university course.

Project requirements

Write an IR system able to answer:

• Boolean queries with AND, OR and NOT;
• Wildcard and phrase queries;
• Provide a way to save and load the entire index from disk, to avoid re-indexing when the program starts;
• Some normalization or stemming can be performed;
• Spelling correction can be implemented;
• Evaluate the system on a set of test queries.

Corpus

The CMU Movie Summary Corpus consists of 42,306 movie plot summaries extracted from Wikipedia and aligned metadata extracted from Freebase.

Getting started

In order to answer queries, the system needs to index the entire corpus first. This operation can take a long time so a pre-built index, located inside the data folder, is used by default for faster start-up. To start the system, just build and run the application. If you want the complete indexing operation to be performed instead, you need to:

1. Download the movie corpus here;
2. Extract the MovieSummaries folder and place it in the project root folder;
3. Delete the pre-built index or move it in another place;
4. Build and run the application.

Query support

As required, the system supports boolean queries, single wildcard queries and two-terms phrase queries.

Boolean queries

Both single- and multiple-term boolean queries are supported. The system expects the boolean operators to be specified in uppercase. By default, if no operators are specified, the query is converted to an AND query. In a NOT query, when multiple terms are specified, the system computes the negation of the OR-ed list of terms.

Example of AND queries

indiana AND jones
rocky balboa adriana
yoda AND luke AND darth
yoda luke darth

Example of OR queries

yoda OR skywalker
yoda OR luke OR darth OR skywalker

Example of NOT queries

NOT the
NOT and is or be are the on at in

Wildcard queries

cat*
catastroph*
c*lly
*atastrophically

Phrase queries

"forrest gump"
"darth maul"
"order 66"
"rocky balboa"
"indiana jones"