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A Semantic Web Oracle.
By Eugen Sawin


Pythia is an experimental platform for semantic web search with keyword queries.

The goal is to translate keyword queries, as typically used with full-text search engines, to semantic queries suitable as input for semantic search engines with high confidence.

The hybrid approach combines full-text search and natural language processing to provide the best search experience.

Required Data

The hybrid approach requires a full-text index and knowledge base.

Currently, the full-text search is conducted via the Google Custom Search API, avoiding the requirement for an index pipeline. Likewise the Freebase API is used for a lightweight access to entity data, in addition to an offline format of the YAGO database.

Due to its huge size, the ontology index is not included in this repository, but will be made available online to allow for reproduction of the system and results.


  • POSIX.1b-compliant operating system (support for librt)
  • GNU Make
  • GNU GCC 4.6+ (sudo apt-get install build-essential)
  • OpenSSL (sudo apt-get install openssl libssl-dev)
  • Python 2.7+ (optional, for style checking)





Building dependencies

To build all dependencies automatically, use:

make depend

Alternatively, you can build each dependency separately by following the instructions here, otherwise you may skip the rest of this section.

Building gflags

The repository contains a slightly modified gflags version with less verbose help output, which is used by default. If you prefer using your installed version, modify the makefile accordingly (follow the comments).

make gflags

Building glog

To build to included glog version, use:

make glog

Building POCO C++ Libraries

To build the POCO submodule, use:

make poco

This will check out the required POCO version from GitHub and build it, which can take a while.

Building SENNA

To get the required SENNA version, use:

make senna

This will download SENNA from the web (~200MB) and modify the source files, so that it compiles with g++. Downloading the files may take a while.

Building Flow

To build the Flow submodule, use:

make flow

Building Pythia

To build Pythia use:


To build the version optimized for speed (-Ofast), use:

make opt

For debugging, use the debug version:

make debug


To start Pythia use:


To show the full usage and flags help use:

./pythia -help

Testing (depends on gtest)

To build and run the unit tests use:

make check

Profiling (depends on gperftools)

To build Pythia with profiling turned on use:

make profile

Getting cpplint

Code style checking depends on a modified version of Google's cpplint. Get it via

make cpplint

Checking style (depends on cpplint)

To test code style conformance with the Google C++ Style Guide use:

make checkstyle


Pythia - A Semantic Web Oracle.
Copyright (C) 2012, 2013 Eugen Sawin

Pythia is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with this program. If not, see

The full copyright notice is contained in the file COPYING.


Semantic web oracle.




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