NAME selt - SE-LTL model checker Part of Tina Toolbox for analysis of Petri nets and Time Petri nets (see also nd, tina, plan, struct, ndrio, ktzio). SYNOPSIS selt [-help] selt ktzfile [-f formula | formfile] [-prelude ltlfile] [-q | -v] [-b | -c | -p | -s | -g] [-S scnfile] [-wp n] [outfile] DESCRIPTION selt model-checks state-event LTL formulas on a kripke tran- sition system given in ktz format. If some formula is specified (by flag -f or by providing formfile), then the result of evaluation of the formula is printed according to the output mode and verbosity flags, and selt exits. If no formulafile is specified, then selt starts an interactive session, evaluating commands entered by the user on standard input (see "selt se-ltl language and commands" below). OPTIONS -help Recalls options. Ktz input: ktzfile The kripke transition system on which formula are model-checked, in ktz format (extension .ktz). -wp (0|1|2) This flag removes (0), preserves (1), or forces at each state (2) the temporal divergence property possi- bly present in the kts file (see tina's -wp flag for details). LTL input: -f formula Passes to selt the formula to be verified. formfile Specifies a file holding the formulas to be verified. Must have extension .ltl -prelude ltlfile Specifies a file containing selt commands to be evaluated on entry, before any formula provided by -f, by formfile, or interactively. This flag is useful to load SE-LTL libraries. ltlfile must have extension .ltl Verbosity level: -v prints banner and evaluation times for LTL commands (default). -q No banner nor times are printed. This flag is useful for batch operation. Output mode flags: -b When evaluating a formula, just prints its truth value, without counter example. -c When a formula evaluates to FALSE, prints in addition a counter example in condensed form (default). -p When a formula evaluates to FALSE, prints in addition a counter example in full form. -s When a formula evaluates to FALSE, prints in addition a counter example in the scn formmat of the nd stepper. -g When a formula evaluates to FALSE, does not print a counter example, but builds the full graph obtained as the synchronization of the kts and of the bucchi automaton translating the negation of the formula, instead, in ktz form (to be provided). Other flags: -S scnfile When a formula evaluates to FALSE, writes a counter example in .scn format of in file scnfile (creating the file if it does not exist, and overwriting it other- wise). This flag is useful to replay counter exam- ples in the nd stepper when modelchecking an existing ktz description and a description of the net the .ktz file describes the behavior of is available (see "interacting with the nd stepper" below). Output destination: outfile Where results are written. The output format is deter- mined by the file type, according to the table below. If absent or specified by "-", then results are writ- ten on standard output in the format specified by the output flag. If both an outfile and some output flag are present, then the format defined by the output flag supersedes that determined by the outfile exten- sion. file extension output format -------------------------------------------------------------- .scn nd stepper .scn format .ktz .ktz format any other textual output FILES File net.txt, ndr.txt, tpn.txt, TPN.rng in directory for- mats specify the syntax of .net, .ndr, .tpn and .pnml net description files, respectively. File formats/scn.txt file specifies the .scn format. EXAMPLES selt abp.ktz -f "[] (t1 => <> t3)" -q -b selt abp.ktz -p INTERACTING WITH THE ND STEPPER For model-checking Petri nets or Time Petri nets, tool selt is interfaced with the nd editor of the Tina toolbox. When the .ktz of the behavior of some net is not available, or rebuilding it is cheap, SE-LTL proper- ties of the net can be model-checked as follows: load the net into nd, then build the ktz description of its behavior (using the reachability tool, with the default output mode and construction), then invoke the model- checker from the menu in the ktz window, and finally select "stepper" in the nd tools menu. Any counter example computed by the model-checker will then be loaded automati- cally into the stepper, for replay. When the .ktz of the behavior of some net is available and rebuilding it is expensive, then invoke selt with option -S. The file passed with -S will always hold the last counter example built. In parallel, load the net description into nd and select "stepper" in the nd tools menu. For replaying a counter example, load the .scn file specified with -S. SELT SE-LTL LANGUAGE AND COMMANDS Selt implements a version of the SE-LTL linear time temporal logic as described in paper: S. Chaki, E. M. Clarke, J. Ouaknine, N. Sharygina, and N. Sinha, "State/Event-based Software Model Checking", 4th International Conference on Integrated Formal Methods (IFM'04), Springer LNCS 2999, pages 128--147, April 2004. For building Buchi automata from LTL files, selt relies on ltl2ba, a tool described in the paper below and available at http://www.liafa.jussieu.fr/~oddoux/ltl2ba P. Gastin and D. Oddoux, "Fast LTL to Buchi Automata Translation", 13th Conference Computer-Aided Verification (CAV'2001), Springer LNCS 2102, pages 53--65, July 2001. 1. Lexical matters: - A identifier is either: Any place or transition identifier allowed in .net or .ndr descriptions, that is: any sequence of letters, digits, underscores "_" and primes "'", or any sequence of characters enclosed in braces in which "{", "}" (except the outer ones) and "\" are prefixed by "\" Any sequence of symbols from the list ~ ` ! @ # $ % ^ & * - + = : ? | / < > [ ]; A qualified identifier: an identifier prefixed by A. or L. e.g. hello, _p4'_, 123, >=<, or {variable x45}, are legal identifiers. - The commands are: op, infix, prefix, forget, verb, output, source. Command names may not be used as operator or variable names. - When analyzing identifiers, the scanner advances as right as possible. So, in a juxtaposition of identifiers, two symbolic or two alphanumeric unbraced identifiers, or e.g. an alphanumeric identifier and a command name, must be separated by a space. But no space is necessary between identifiers of different kinds or between a parenthesis (or ";") and an identifier. - justaposition bind tighter than infixes and associate to the left, infixes and prefixes associate to the right. That is, if f is a 3-ary operator in functional notation, [], <>, -, are prefixes, and /\, \/, are infixes: [] p1 => <> - p3 /\ f u v w parses as ([] p1) => ((<> (- p3)) /\ (f u v wp)) f - <> p1 (f p0 p1 (p4 /\ p5)) \/ f u v w parses as (f (- <> p1) (f p0 p1 (p4 /\ p5))) \/ (f u v w) and f - <> p1 f p0 p1 p4 \/ f u v w parses as (f (- <> p1) f p0 p1 p4) \/ (f u v w) which is ill-typed - infixes have precedence in 0..3 (see below). Infixes with higher precedence bind tighter than those with lower precedence. 2. The initial environment: It is made up of (pushed in that order): - The atomic state and event propositions. They have the names captured in the .ktz file, i.e. those of the places and transitions of the Petri net if the .ktz file was generated by tina. - Then, the logic and arithmetic primitives, constituted of: constants: T (true), F (false), dead (deadlock property) div (temporal divergence property) prefixes: [] (always), <> (eventually), () (next), - (negation) infixes: /\ (and), \/ (or), => (implies), <=> (equivalent), U (until), V (release), of precedence 0 <=, >=, =, of precedence 1, +, of precedence 2 *, of precedence 3 - Then the user defined operators. Since the syntactic classes of atomic proposition, logic primitives, integer. and user defined operators, overlap, we must have some way of disambiguating identifiers. For this: - unqualified identifiers are bound to the command with than name, if any, or otherwise to the last pushed environment entry with that name. - identifiers qualified by A (e.g. A.p1) are bound to the atomic proposition with that name with the qualifier removed (e.g. p1); - identifiers qualified by L (e.g. L./\) are bound to the logic primitive with that name with the qualifier removed (e.g. /\); So, atomic propositions (found in the ktz file) sharing their name with some command (e.g. op) or with some logical primitive (e.g. -), or the name of which is an integer (e.g. 3), must be referred to in formulas by their qualified form (e.g. A.op, A.-, or A.3); 3. Fixity: Identifiers declared infix (binary logic primitives or user defined operators declared by "infix") must be used in infix notation; Identifiers declared prefix (unary logic primitives or user defined operators declared by "prefix") must be used in prefix notation (in a juxtaposition of identifiers, prefix operators associate with the right expression); Other operators or primitives accessed by their qualified names must be used in functional notation. E.g. if a1, a2, a3 are parenthesized expressions, and f has arity 3, then: a1 /\ a2 and L./\ a1 a2 are legal (and equivalent) but a1 L./\ a2 is ill-typed f - a1 a2 a3 is legal (parses as ((f (- a1)) a2) a3) but f L.- a1 a2 a3 T is ill-typed (parses as (((f L.-) a1) a2) a3) 4. Commands and effects: Commands must terminate with ";". In formula files, the final ";" may be omitted (EOF plays that role). The effects of commands are as follows ("exp" is any ltl expression, x, y, f, xi are identifiers): exp; evaluates LTL expression exp; op f x1 ... xn = exp; declares an operator f or arity n (n >= 0), to be used in functional notation; infix [n] x f y = exp; declares a binary operator f in infix notation. n is an optional integer in 0..3 specifying precedence. prefix f x = exp; declares a unary operator f in prefix notation; forget f1 ... fn; Removed items names f1 ... fn from the environment, and their fixity information; source [file | "file"]; reads at toplevel the contents of file. The file name is optionally surrounded by string quotes (this is necessary if the name includes spaces); verb [true | false | debug]; verbosity level. Tne initial setting follows from the command line flags -v | -q (default -v); true (default): prints the banner, prompts, results of commands, and evaluation times; false: just prints the results of evaluation of LTL expressions (useful in batch mode); debug: may print extra information (mainly for developper); output [proof | fullproof | quiet | stepper | graph] specify effects and results of evaluations of LTL expressions. The command line flags -c, -p, -b, -s, -g specifies the initial setting (default -c); proof (default): evaluations return TRUE, or FALSE with a counter example in condensed form; fullproof: evaluations return TRUE, or FALSE with a counter example in full form (may be very large); quiet: evaluations just return TRUE or FALSE, without counter examples. stepper: as output fullproof except the counter example is in stepper format (typically used in batch mode); graph: not implemented yet quit leaves selt (also ^D on Unix targets). 5. Example commands: p1; (eqv. p1 >= 1) - p1; (eqv. p1 = 0) p1 /\ p2 >= 2; (eqv. p1 /\ (p2 >= 2)) op x > y = x >= y + 1; (declares arithmetic operator >, in infix form) p1+p2; (eqv. p1+p2 >= 0, eqv. p1 \/ p2) p1+p2 > p3; p1*p2 = 0; infix y follows x = [] (x => <>y); (declares logocal operator "follows:, in infix form) (t3 \/ p5) follows (t1 /\ p1>=p2); (eqv. [] ((t1 /\ (p1>=p2)) => <> (t3 \/ p5))); FILES Files scn.txt and ktz.scn in directory formats specify the syntax of scenario .scn files and .ktz transition system files, respectively. SEE ALSO nd, tina, plan, struct, ndrio, ktzio AUTHORS Bernard Berthomieu, Pierre-Olivier Ribet, LAAS/CNRS, 2000- 2005, Bernard.Berthomieu@laas.fr.