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Manual Reference Pages - walk (n)

### NAME

> walk - Tina random walk explorer

> Part of Tina Toolbox for analysis of Petri nets and Time Petri nets.

### CONTENTS

> Synopsis
> Description
> Options
> Examples
> See Also
> Authors

### SYNOPSIS

> walk [-help] [-p]
> [-R | -P | -V | -Q | -Z(v|i|vi)]
> [-T[,(min|max|rand)][,(dense|discrete)] | -W | -S]
> [-f form | -dead] [-c n] [-t s] [-b n]
> [-seed] [-loop | -repeat] [-only s] [-favor s] [-avoid s] [-never s]
> [-q | -v] [-NET | -NDR | -TPN | -PNML | -TTS]
> [-inh] [-tc] [-dt] [-pr] [-sw] [-stats] [-trace]
> [infile] [outfile] [digestfile] [errorfile]

### DESCRIPTION

> Tool walk allows to simulate net descriptions in any of formats .net, .ndr, .tpn, .pnml or .tts. Its capabilities include those provided by the play tool except that walk is not interactive and never stores history. walk is typically much faster than play and provides more simulation modes; its primary intent is to quickly find counter examples to reachability properties in a random walk over markings, timed state markings, or state class markings.

### OPTIONS

> -help | Recalls options.
> Marking paths specification:
> If there are no time constraints in the input net, then a path is a sequence of net markings separated by net transitions or steps (sets of transitions fired simultaneousy).
> -R | Path transitions are single net transitions.
> -P | The path transitions are firing sequence in the partial marking graph built by the persistent set method.
> -V | The path transitions are steps in the partial marking graph built by the covering steps method.
> -Q | The path transitions are steps of the partial marking graph built by the persistent steps method (combining -P and -V construction, see tina papers for details).
> -Zv | -Zi | -Zvi
> | The path transitions are steps of the marking graphs built by three "maximal steps" firing rules: -Zv, or -sleptsov: a step at marking m is an enabled transition t fired at its maximum enabledness multiplicity at m; that is a bag t*k, where k is the largest integer such that t is firable k times simultaneously at m; -Zi, or -salwicki: a step at m is a maximal set of transitions simultenaously firable at m; -Zvi, or -slepsalw: a combination of -Zv and -Zi. A step at m is a maximal bag of transitions simultenaously firable at m; These options remove time constraints. In addition, options -Zi and -Zvi remove priorities.
> Timed state paths specification:
> If the input net is a Time Petri net with nontrivial time constraints, then a path is either a series of states
> | separated by transitions (delay transitions followed by discrete transitions) in the -T construction, or a series of state classes separated by discrete transitions in the -W and -S constructions.
> -T[,(min|max|rand)][,(dense|discrete)]
> | Each path transition is a delay followed by a net transition. One may specify that delays are the minimum allowed, maximum allowed, or ca be choosen randomly between these. The semantics of time is either discrete (integer time instants only0 or dense. If the input net is not timed or all transition delays are trivisl ([0,w[), then -T is silently handed as -R.
> -W | -S | States are state classes (-W) or strong state classes (-S). Path transitions are net transitions, time delays are abstracted.
> Path constraints:
> -seed | Initializes the random number generator so that different calls of walk on the same arguments have a chance to explore different paths (if any).
> -loop | If the current state is a deadlock and it is not a counter example to the property to be checked, then the simulation is restarted from the initial state.
> -repeat | Same as -loop except does not restart on reaching a time or path length limit.
> -favor s | -avoid s
> | Whevener possible along the path, pick transitions in s (-favor s), or not in s (-avoid s). If s is a file, then the set considered is the contents of file s.
> -only s | -never s
> | Restrict path to the transitions in s (-only s), or not in s (-never s). If not possible, then the path is terminated. If s is a file, then the set considered is the contents of file s.
> Stopping conditions:
> | Flags -f and -dead specify formulas that should be invariant. walk stops along a path if some state violating the specified formula is found.
> -f form | Stop with result FALSE if some state does not obey property form; no effects if form=T. Stops with result OPEN if no counter example was found along the path developped. Formula form is any modality-free formula accepted by the selt model checker (check man selt for details). In addition, an atomic proposition is provided, "safe" or "L.safe", then asserts that the marking of each place does not exceed 1. If form is a file, then the formula considered is the contents of file form. As of Version 4.0.0, the input formula passed by -f may be a set of formulas, represented by a string (possibly in a file) in which individual formulas are separated by a semicolon. At each step, all open formulas are evaluated at the current state. If some formula is resolved then a suitable message is printed on the fly on stdout. Formulas in a set are referred to by their index in the set description. walk terminates when no more open formula is left or by one of the limit options.
> -dead | Stop with FALSE if some deadlock state is found; shorthand for -f "-L.dead".
> -c n | walk stops with result OPEN if the length of the path taken exceeds n (unless -loop passed).
> -t s | walk stops with result OPEN if more than s seconds elapsed since walk was called.
> -b n | Stops with FALSE if some marking is found that marks some place with more than n tokens.
> Input options:
> -inh | Forget inhibitor and read arcs in the input net.
> -pr | Forget priority constraints in the input net.
> -tc | Forget time constraints in the input net.
> -dt | Forget data processing when reading a tts description.
> -sw | Forget stopwatch and stopwatch-inhibitor arcs in the input net.
> Input format and source:
> -NET | -NDR | -PNML | -TPN | -TTS
> | Specifies the format of the input net. This flag is necessary when the input net is read on standard input, or read from a file that does not bear the expected extension. By default, the net is assumed in .net or
> infile | Where the net is read. The input format is determined by the file type, according to the table below. If absent or specified by "-", the net is read on standard input in the format specified by the input flag. If both an infile and some input flag are present, then the format defined by the input flag supersedes that determined by the infile extension.
>     file extension          input format
>     --------------------------------------------------------------
>     .net                    net format
>     .ndr                    ndr format
>     .tpn                    tpn format
>     .pnml                   pnml format
>     .tts                    tts format
> Output format and destination:
> -q | -v | Verbosity level, quiet (-q) or verbose (-v).
> outfile
> | Where results are written. If absent or specified by "-", results are written on standard output.
> Digest destination:
> digestfile
> | In addition to (possibly) its results in file outfile, walk may prints a summary of results in file digestfile (default stdout).
> Errors destination:
> errfile
> | Where error messages are written. If absent or specified by "-", error messages are written on standard error.
> Other flags:
> -stats | prints progress information on the fly (path length so far).
> -trace | prints path transitions on the fly, prefixed by delays if input is timed.

### EXAMPLES

>     walk -T,min,dense -f L.safe ../nets/ifip.ndr
>     walk -R -dead AirplaneLD-PT-0010.pnml
>     walk -W -f -t4 ../nets/ifip.ndr
>     walk -W -f -p3 ../nets/ifip.ndr

### SEE ALSO

> nd(n), tina(n), plan(n), struct(n), ktzio(n), ndrio(n), tedd(n), selt(n), sift(n), muse(n), pathto(n), scan(n), play(n), reduce(n), formats(n), stan(n)

### AUTHORS

> Bernard Berthomieu LAAS/CNRS, 2000-2026, Bernard.Berthomieu@laas.fr

Tina Tools | walk (n) | Version 4.0.0

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