[ltl-lib] Import code.

AUTHORS

LICENSE

README.md

build.gradle

src/main/java/ltl/BinaryVisitor.java

src/main/java/ltl/BooleanConstant.java

src/main/java/ltl/Collections3.java

src/main/java/ltl/Conjunction.java

src/main/java/ltl/ContainsVisitor.java

src/main/java/ltl/Disjunction.java

src/main/java/ltl/FOperator.java

src/main/java/ltl/Formula.java

src/main/java/ltl/GOperator.java

src/main/java/ltl/ImmutableObject.java

src/main/java/ltl/ImplicationVisitor.java

src/main/java/ltl/Literal.java

src/main/java/ltl/ModalOperator.java

src/main/java/ltl/PatientSlaveVisitor.java

src/main/java/ltl/PropositionalFormula.java

src/main/java/ltl/PseudoSubstitutionVisitor.java