tulip.spec.gr1_fragment: Test if given formula belongs to an LTL fragment that is
convertible to deterministic Buchi Automata (readily expressible in
GR(1) ).
tulip.spec.lexyacc: PLY-based parser for TuLiP LTL syntax, using AST classes from
spec.ast
tulip.spec.parser: LTL parser supporting JTLV, SPIN, SMV, and gr1c syntax