Journal of Logic and Computation Advance Access published online on February 6, 2008
Journal of Logic and Computation, doi:10.1093/logcom/exn002
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Original papers |
A Syntactical Proof of the Canonical Reactivity Form for Past Linear Temporal Logic
Institute of Mathematics and Informatics, Bulgarian Academy of Sciences, Sofia, Bulgaria.
E-mail: gelevdp{at}math.bas.bg
Received 22 January 2007.
| Abstract |
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We present a new proof of the fact that every formula in linear temporal logic with past is equivalent to a formula of the form
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i and βi are past formulas, which is known as general canonical reactivity form. The original proof is based on the fact that a finite automaton recognizes an LTL-definable
-language iff it is counter-free, which was proved in Lenore Zuck's thesis and relies on the theorem of Krohn-Rhodes about cascade decomposition of finite automata. Unlike that, the proof presented in this paper involves only equivalence transformations of LTL formula and makes use of Gabbay's separation theorem, whose proof is based on equivalence transformations too. This makes it possible to obtain the canonical form without resorting to constructions outside LTL with past operators such as automata.
Keywords: Linear temporal logic; canonical reactivity normal form; separation
