CTL

CTL can refer to:

Companies

Computing

CTL*

CTL* is a superset of computational tree logic (CTL) and linear temporal logic (LTL). It freely combines path quantifiers and temporal operators. Like CTL, CTL* is a branching time logic. The formal semantics of CTL* formulae are defined with respect to a given Kripke structure.

History

LTL has been proposed for the verification of computer programs first by Amir Pnueli in 1977. Four years later in 1981 E. M. Clarke and E. A. Emerson invented CTL and CTL model checking. CTL* was defined by E. A. Emerson and Joseph Y. Halpern in 1986.

Interestingly, CTL and LTL have been developed independently before CTL*. Both sublogics have become standards in the model checking community, while CTL* is of practical importance because it provides an expressive testbed for representing and comparing these and other logics. This is surprising because the computational complexity of model checking in CTL* is not worse than that of LTL: they both lie in PSPACE.

Syntax

The language of well-formed CTL* formulae is generated by the following unambiguous (wrt bracketing) context-free grammar: