# Extracting Symbolic Transitions from $TLA+$ Specifications

2 VERIDIS - Modeling and Verification of Distributed Algorithms and Systems
MPII - Max-Planck-Institut für Informatik, Inria Nancy - Grand Est, LORIA - FM - Department of Formal Methods
Abstract : In TLA+, a system specification is written as a logical formula that restricts the system behavior. As a logic, TLA+ does not have assignments and other imperative statements that are used by model checkers to compute the successor states of a system state. Model checkers compute successors either explicitly-by evaluating program statements-or symbolically-by translating program statements to an SMT formula and checking its satisfiability. To efficiently enumerate the successors, TLA's model checker TLC introduces side effects. For instance, an equality x = e is interpreted as an assignment of e to the yet unbound variable x. Inspired by TLC, we introduce an automatic technique for discovering expressions in TLA+ formulas such as x = e and x ∈ {e1,. .. , e k } that can be provably used as assignments. In contrast to TLC, our technique does not explicitly evaluate expressions, but it reduces the problem of finding assignments to the satisfiability of an SMT formula. Hence, we give a way to slice a TLA+ formula in symbolic transitions, which can be used as an input to a symbolic model checker. Our prototype implementation successfully extracts symbolic transitions from a few TLA+ benchmarks.
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Cited literature [26 references]

https://hal.inria.fr/hal-01871131
Contributor : Igor Konnov <>
Submitted on : Monday, September 10, 2018 - 1:53:01 PM
Last modification on : Tuesday, February 19, 2019 - 3:40:04 PM
Long-term archiving on: : Tuesday, December 11, 2018 - 2:41:54 PM

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Jure Kukovec, Thanh-Hai Tran, Igor Konnov. Extracting Symbolic Transitions from $TLA+$ Specifications. Abstract State Machines, Alloy, B, TLA, VDM, and Z. ABZ 2018, Jun 2018, Southampton, United Kingdom. pp.89-104, ⟨10.1007/978-3-319-91271-4_7⟩. ⟨hal-01871131⟩

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