Manual Reference Pages  - walk (n)


walk - Tina random walk explorer

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


See Also


walk [-help] [-p]
[-R | -P | -V | -Q]
[-T[,(min|max|rand)][,(dense|discrete)] | -W | -S]
[-f formula | -ff file | -dead] [-c n] [-t s] [-b n]
[-seed] [-loop] [-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]


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.


-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 sequences of steps in the partial marking graph built by the covering steps method.

-Q The path transitions are sequences of steps in the partial marking graph built by the persistent steps method (combining -P and -V construction, see tina papers for details).

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.

  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 or terminated due to other path consttaints, and it is not a counter example to the property to be checked, then the simulation is restarted from the initial marking or state.

-favor s | -avoid s
  Whevener possible along the path, pick transitions in s (-favor s), or not in s (-avoid s).

-only s | never s
  Restrict path to the transitions in s (-only s), or not in s (-never s). If not possible, then terminate the path.

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 "", then asserts that the marking of each place does not exceed 1.

-ff form Equivalent to -f form, for the formula form read in file.

-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.

-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 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).

  Where results are written. If absent or specified by "-", results are written on standard output.

Digest destination:

  In addition to (possibly) its results in file outfile, walk may prints a summary of results in file digestfile (default stdout).

Errors destination:

  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.


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


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


Bernard Berthomieu LAAS/CNRS, 2000-2012,

Tina Tools walk (n) Version 3.7.0
Generated by manServer 1.07 from src/walk.n using man macros.