spot/doc/org/autfilt.org

autfilt

• Conversion between formats
• Displaying statistics
• Simplifying automata

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The autfilt tool can filter, transform, and convert a stream of automata.

Conversion between formats

autfilt reads automata in the Hanoi Omega Automata Format. The output format can be controlled using the --spin, --lbtt, --dot, or --hoaf options.

cat >example.hoa <<EOF
HOA: v1
States: 1
Start: 0
AP: 1 "p0"
Acceptance: 1 Inf(0)
--BODY--
State: 0
[0] 0 {0}
[!0] 0
--END--
EOF
autfilt example.hoa --dot

digraph G {
  0 [label="", style=invis, height=0]
  0 -> 1
  1 [label="0"]
  1 -> 1 [label="p0\n{0}"]
  1 -> 1 [label="!p0"]
}

The --spin options implicitly requires a degeneralization:

autfilt example.hoa --spin

never {
accept_init:
  if
  :: ((p0)) -> goto accept_init
  :: ((!(p0))) -> goto T0_S2
  fi;
T0_S2:
  if
  :: ((p0)) -> goto accept_init
  :: ((!(p0))) -> goto T0_S2
  fi;
}

autfilt example.hoa --lbtt

1 1t
0 1
0 0 -1 p0
0 -1 ! p0
-1

Displaying statistics

One special output format of autfilt is the statistic output. For instance the following command calls randaut to generate 10 random automata, and pipe the result into autfilt to display various statistics.

randaut --hoa -n 10 -A0..2 -S10..20 -d0.05 2 |
autfilt --stats='%s states, %e edges, %a acc-sets, %c SCCs, det=%d'

16 states, 27 edges, 1 acc-sets, 2 SCCs, det=0
12 states, 20 edges, 1 acc-sets, 2 SCCs, det=0
11 states, 15 edges, 0 acc-sets, 4 SCCs, det=1
16 states, 29 edges, 0 acc-sets, 2 SCCs, det=0
15 states, 30 edges, 2 acc-sets, 1 SCCs, det=0
11 states, 17 edges, 1 acc-sets, 2 SCCs, det=0
11 states, 16 edges, 1 acc-sets, 1 SCCs, det=1
17 states, 28 edges, 1 acc-sets, 1 SCCs, det=0
19 states, 36 edges, 0 acc-sets, 3 SCCs, det=0
11 states, 16 edges, 2 acc-sets, 6 SCCs, det=0

The following % sequences are available:

  %%                         a single %
  %A, %a                     number of acceptance pairs or sets
  %C, %c                     number of SCCs
  %d                         1 if the output is deterministic, 0 otherwise
  %E, %e                     number of edges
  %F                         name of the input file
  %n                         number of nondeterministic states in output
  %p                         1 if the output is complete, 0 otherwise
  %r                         conversion time (including post-processings, but
                             not parsing) in seconds
  %S, %s                     number of states
  %T, %t                     number of transitions

When a letter is available both as uppercase and lowercase, the uppercase version refer to the input automaton, while the lowercase refer to the output automaton. Of course this distinction makes sense only if autfilt was instructed to perform an operation on the input automaton.

Simplifying automata

The standard set of automata simplification routines (these are often referred to as the "post-processing" routines, because these are the procedures performed by ltl2tgba after translating a formula into a TGBA) are available through the following options.

This set of options controls the desired type of output automaton:

  -B, --ba                   Büchi Automaton
  -M, --monitor              Monitor (accepts all finite prefixes of the given
                             property)
      --tgba                 Transition-based Generalized Büchi Automaton
                             (default)

These options specifies desired properties:

  -a, --any                  no preference (default)
  -C, --complete             output a complete automaton (combine with other
                             intents)
  -D, --deterministic        prefer deterministic automata
      --small                prefer small automata

Finally, the following switches control the amount of effort applied to reach the desired properties:

      --high                 all available optimizations (slow)
      --low                  minimal optimizations (fast, default)
      --medium               moderate optimizations