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Automata, Languages and Programming

Volume 2719 of the series Lecture Notes in Computer Science pp 767-775

Date:

CTL+ Is Complete for Double Exponential Time

  • Jan JohannsenAffiliated withInstitut für Informatik, Ludwig-Maximilians-Universität München
  • , Martin LangeAffiliated withInstitut für Informatik, Ludwig-Maximilians-Universität München

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Abstract

We show that the satisfiability problem for CTL+, the branching time logic that allows boolean combinations of path formulas inside a path quantifier but no nesting of them, is 2-EXPTIME-hard. The construction is inspired by Vardi and Stockmeyer’s 2-EXPTIME-hardness proof of CTL*’s satisfiability problem. As a consequence, there is no subexponential reduction from CTL+ to CTL which preserves satisfiability.