Its main focus lies on memory-efficient data-structures for Boolean formulas and efficient algorithms for manipulating and solving them. The library is designed to be used in industrial systems which have to manipulate and solve millions of formulas per day.
The most important philosophy of the library is to avoid unnecessary object creation. Therefore formulas can only be generated via formula factories. A formula factory assures that a formula is only created once in memory. If another instance of the same formula is created by the user, the already existing one is returned by the factory. This leads to a small memory footprint and fast execution of algorithms. Formulas can cache the results of algorithms executed on them and since every formula is hold only once in memory it is assured that the same algorithm on the same formula is also executed only once.
Compared to other implementation of logic libraries on the JVM this is a huge memory and performance improvement.
LogicNG is released in the Maven Central Repository. To include it just add
<dependency> <groupId>org.logicng</groupId> <artifactId>logicng</artifactId> <version>2.0.2</version> </dependency>
to your Maven POM.
master branch contains the latest release of LogicNG. If you want a stable and well tested version you should choose this branch. The
development branch reflects the current state of the next version. This branch will always compile, but code might not be as well tested and APIs may still change before the next release. If you want to try cutting edge features, you can checkout this branch at your own risk. It is not recommended to use the development version for production systems. Larger features will be developed in their own branches and will be merged to the development branch when ready.
To compile LogicNG simply run
mvn compile to build the parsers and compile the source code. You can build a jar of the library with
mvn package or install it in your local maven repository via
The following code creates the Boolean Formula A and not (B or not C) programatically:
final FormulaFactory f = new FormulaFactory(); final Variable a = f.variable("A"); final Variable b = f.variable("B"); final Literal notC = f.literal("C", false); final Formula formula = f.and(a, f.not(f.or(b, notC)));
Alternatively you can just parse the formula from a string:
final FormulaFactory f = new FormulaFactory(); final PropositionalParser p = new PropositionalParser(f); final Formula formula = p.parse("A & ~(B | ~C)");
Once you created the formula you can for example convert it to NNF or CNF or solve it with an instance of MiniSAT:
final Formula nnf = formula.nnf(); final Formula cnf = formula.cnf(); final SATSolver miniSat = MiniSat.miniSat(f); miniSat.add(formula); final Tristate result = miniSat.sat();
Frequently Asked Questions
We recently started a Wiki section for a FAQ.
License & Commercial Support
The library is released under the Apache License and therefore is free to use in any private, educational, or commercial projects. Commercial support is available through the German company BooleWorks GmbH - the company behind LogicNG. Please contact Christoph Zengler at email@example.com for further details.