Graal is a Java toolkit for querying knowledge bases within the framework of existential rules, aka Datalog+/-. See Graal's homepage:
clone the repository
git clone https://github.com/graphik-team/graal.git
build the project
mvn package
mvn javadoc:javadocmvn javadoc:aggregate
mvn pmd:checkmvn findbugs:check
./prepare_ant.shant