imclab / openie

Quality information extraction at web scale.

Open IE

This project contains the principal Open Information Extraction (Open IE) system from the University of Washington (UW). An Open IE system runs over sentences and creates extractions that represent relations in text. For example, consider the following sentence.

The U.S. president Barack Obama gave his speech on Tuesday to thousands of people.

There are many binary relations in this sentence that can be expressed as a triple (A, B, C) where A and B are arguments, and C is the relation between those arguments. Since Open IE is not aligned with an ontology, the relation is a phrase of text. Here is a possible list of the binary relations in the above sentence:

(Barack Obama, is the president of, the U.S.)
(Barack Obama, gave, his speech)
(Barack Obama, gave his speech, on Tuesday)
(Barack Obama, gave his speech, to thousands of people)

The first extraction in the above list is a "noun-mediated extraction", because the extraction has a relation phrase is described by the noun "president". The other extractions are very similar. In fact, they can be represented more informatively as an n-ary extraction. An n-ary extraction can have 0 or more secondary arguments. Here is a possible list of the n-ary relations in the sentence:

(Barack Obama, is the president of, the U.S.)
(Barack Obama, gave, [his speech, on Tuesday, to thousands of people])

Extractions can include more than just the arguments and relation as well. For example, we might be interested in whether the extraction is a negative assertion or a positive assertion, or if it is conditional in some way. Consider the following sentence:

Some people say Barack Obama was born in Kenya.

We would not want to extract that (Barack Obama, was born, in Kenya) alone because this is not true. However, if we have the condition as well, we can have a correct extraction.

Some people say:(Barack Obama, was born in, Kenya)

To see an example of Open IE being used, please visit http://openie.cs.washington.edu/.

Research

Open IE 4.0 is the successor to Ollie. Whereas Ollie used bootstrapped dependency parse paths to extract relations (see Open Language Learning for Information Extraction), Open IE 4.0 uses similar argument and relation expansion heuristics to create Open IE extractions from SRL frames. Open IE 4.0 also extends the defintion of Open IE extractions to include n-ary extractions (extractions with 0 or more arguments 2s).

Buiding

openie uses java-7-openjdk & the sbt build system, so downloading dependencies and compiling is simple. Just run:

sbt compile

Running

You can run openie with sbt or create a stand-alone jar. openie requires substantial memory. sbt is configured to use these options by default:

-Xmx4G -XX:+UseConcMarkSweepGC

Running with sbt

sbt 'run-main edu.knowitall.openie.OpenIECli'

Running from a stand-alone jar.

First create the stand-alone jar.

sbt clean compile assembly

You may need to add the above memory options.

sbt -J-Xmx2700M clean compile assembly

Then you can run the resulting jar file as normal.

java -jar openie-assembly.jar

You may need to add the above memory options.

java -Xmx4g -XX:+UseConcMarkSweepGC -jar openie-assembly.jar

Command Line Interface

openie takes one sentence per line unless --split is specified. If --split is specified, the input text will be split into sentences. You can either pipe input from Standard Input, specify an input file (an option first argument), or type sentences interactively. Output will be written to Standard Output unless a second option argument is specified for an output file.

openie takes a number of command line arguments. To see them all run java -jar openie-assembly.jar --usage. Of particular interest are --ignore-errors which continues running even if an exception is encountered, --binary which gives the binary(triples) output and --split which splits the input document text into sentences.

There are two formats--a simple format made for ease of reading and a columnated format used for machine processing. The format can be specified with either --format simple or --format column. The simple format is chosen by default.

Simple Format

> John ran down the road to fetch a pail of water.
John ran down the road to fetch a pail of water.
0.86 (John; ran; down the road; to fetch a pail of water)
0.82 John ran:(John; ran down the road to fetch; a pail of water)

Columnated Format

Columns are separated by tab, making it hard to read in this README.

0.8576784836790008	John	ran	down the road; to fetch a pail of water	John ran down the road to fetch a pail of water.
0.8195727266148489	John ran	John	ran down the road to fetch	a pail of water	John ran down the road to fetch a pail of water.

Contributors

• Michael Schmitz (http://www.schmitztech.com/)
• Bhadra Mani