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The Alpha solver for lazy-grounding Answer-Set Programming.
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Alpha is an Answer Set Programming (ASP) system: It reads a logic program (a set of logical rules) and computes the corresponding answer sets. ASP falls into the category of declarative and logic programming. Its applications are solving combinatorial problems, but it also is a good tool for reasoning in the context of knowledge-representation and databases.

Alpha is the successor of OMiGA and currently in development. In contrast to many other ASP systems, Alpha implements a lazy-grounding approach in hopes of overcoming memory constraints when working with large input.

Alpha is not the fastest system available, since its goal is not to be the fastest system with current technology but to explore new technologies rapidly. Those technologies, like lazy-grounding, allow Alpha to succeed where other ASP systems fail completely. The project deliberately chooses to trade shorter execution times (which would be possible by using unmanaged runtimes, e.g. C/C++, and low-level optimization) for a more straight forward system design and possibilities to interface with the ecosystem built around the Java Virtual Machine.

Getting Started

Download a current version of alpha.jar from Releases.

Running Alpha is as simple as running any other JAR:

$ java -jar alpha.jar

Example Usage

Solve 3-colorability for some benchmarking instance and filter for color predicates:

$ java -jar alpha.jar -i benchmarks/omiga/omiga-testcases/3col/3col-10-18.txt -fblue -fred -fgreen

Note that in this example the path to the input file is relative to the root of this repository. If you have not checked out the repository, you can just download the example file from GitHub.


Alpha uses the Gradle build automation system. Executing

$ gradle build

will automatically fetch all dependencies (declared in build.gradle) and compile the project.

Artifacts generated will be placed in build/. Most notably you'll find files ready for distribution at build/distributions/. They contain archives which in turn contain a bin/ directory with scripts to run Alpha on Linux and Windows.

If you want to generate a JAR file to be run standalone, execute

$ gradle bundledJar

and pick up build/libs/alpha-bundled.jar.

Suggested Reading

Research Papers on Alpha

Similar Work

  • Smodels, a solver usually used in conjunction with lparse.
  • DLV
  • ASPeRiX, a solver that implements grounding-on-the-fly.
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