Natural Logic Inference for Common Sense Reasoning
C++ TeX Java C Shell Python Other
Switch branches/tags
Nothing to show
Clone or download
Latest commit 8a29fc4 Jun 20, 2017


Natural [Language|Logic] Inference

Build status

NaturalLI is a Natural Logic reasoning engine aimed at fast inference from a large database of known facts. The project's primary goal is to infer whether arbitrary common-sense facts are true, given a large database of known facts. The system is described in:

Gabor Angeli and Christopher D. Manning. "NaturalLI: Natural Logic for Common Sense Reasoning." EMNLP 2014.


Quick Start

On Ubuntu, the program can be built (including all dependencies) with:

./  # optional; read this before running it!
make install  # optional; make sure to set --prefix appropriately

Compiler Versions

The code compiles with both g++ (4.8+; 4.9+ highly recommended) and clang++ (4.5+). With GCC 4.8, regular expressions will not work properly, which means sending flags to the C program will not work properly (an exception will be raised and the program will crash).

On Ubuntu, you can install g++ 4.9 with:

sudo add-apt-repository ppa:ubuntu-toolchain-r/test
sudo apt-get update
sudo apt-get install g++-4.9

Clang should already be at a new enough version as of Ubuntu 14.04 and onwards.

Configuration Options

The following is a list of options that can be passed into the configure script, and a description of each.

  • --enable-debug: Enables code coverage and assertions.

  • --with-java: The root of the Java runtime to use. This should be Java 8+, and must include both java and javac (i.e., not just a JRE).

  • --with-corenlp: The location of CoreNLP -- generally, a Jar file. This must be CoreNLP Version 3.5.3 or newer. Must be an absolute path!

  • --with-corenlp-models: The location of the CoreNLP models jar. Must be an absolute path!

  • --with-corenlp-caseless-models: The location of the CoreNLP caseless models jar. Must be an absolute path!

In addition, a number of environment variables are relevant for the configure script. These are listed below:

  • CXX: The C compiler to use. Both g++ (4.8+; 4.9+ highly recommended) and clang++ (3.5+) should compile.

  • MAX_FACT_LENGTH: The maximum number of tokens a fact can be. This has to be less than 255.

  • MAX_QUERY_LENGTH: The maximum length of a query. Note that memory during search scales linearly with this value. Default is 39. Default value has nice cache-alignment properties.

  • MAX_QUANTIFIER_COUNT: The maximum number of quantifiers in a sentence. Note that search memory and search runtime scales linearly with this. Default is 6. Default value has nice cache-alignment properties.

  • SERVER_PORT: The port to serve the server from. Default is 1337.

  • SEARCH_TIMEOUT: The maximum number of ticks to search for. Default is 1000000.

  • SEARCH_CYCLE_MEMORY: The depth to backtrack during seach looking for cycles. Lower values cause search to run faster, but nodes to be repeated more often. Default is 3.

  • SEARCH_CYCLE_FULL_MEMORY: Check all the way back to the start node for cycles. Default is false (0).

  • MAX_FUZZY_MATCHES: The number of premises to consider from the explicit premise set for fuzzy alignment matches. Default is 0.

  • MAX_BRANCHOUT: The maximum branching factor of the graph search. This is to prevent runaway nodes from taking too much time. Default is 100.


Command Line Inference

The NaturalLI interface takes as input lines from standard in, and outputs JSON output to standard out (with debugging information on stderr). You can therefore run the program simply by running:


You can then enter premise/hypothesis pairs as a series of sentences, one per line. All but the last sentence are treated as a premise; the last sentence is treated as the hypothesis. A double-newline (i.e., a blank line) marks the end of an example. You can also mark hypotheses as True or False; this will cause the program to exit with a nonzero error code if some of the hypothesis are not what they are annotated as. The error code corresponds to the number of failed examples.

For example:

# This is a comment
All cats have tails
Some cats have tails

# This is a new example
# The "True: " prepended to the hypothesis denotes that we expect
# this fact to be true given the premises
Some cats have tails
An irrelevant premise
True: Some animals have tails

A useful side-effect of this framework is the ability to pipe in test files, and get as output annotated json. For example, the test cases for the program can be run with:

cat test/data/testcase_wordnet.examples | src/naturalli

Internet Inference

In addition to the command line interface, you can also talk to the program via a websocket. By default, NaturalLI listens on port 1337; the communication protocol is exactly the same as the command line interface. For example:

$ telnet localhost 1337
Connected to localhost (
Escape character is '^]'.
all cats have tails
some cats have tails