automaton.is_standard

Whether an automaton is standard, i.e.:

  • a single initial state
  • whose (initial) weight is 1
  • without incoming transitions

See also:

Examples

In [1]: 
import vcsn
b = vcsn.context('lal_char(abc), b')
a = b.ratexp('a').standard() | b.ratexp('b').standard()
a
Out[1]:
%3 I0 0 0 I0->0 I2 2 2 I2->2 F1 F3 1 1 0->1 a 1->F1 3 3 2->3 b 3->F3
In [2]: 
assert(not a.is_standard())
assert(a.standard().is_standard())
In [3]: 
a = vcsn.automaton('''
digraph {
  vcsn_context = "lal_char(abc), z"
   I -> 0 [label = "<2>"]
   0 -> 1 [label = "a"]
   1 -> F
}''')
a
Out[3]:
%3 I0 0 0 I0->0 ⟨2⟩ F1 1 1 0->1 a 1->F1
In [4]: 
assert(not a.is_standard())
assert(a.standard().is_standard())
In [5]: 
a = vcsn.automaton('''
digraph {
  vcsn_context = "lal_char(abc), z"
   I -> 0 -> F [label = "<2>"]
   0 -> 1 [label = "a"]
   1 -> 0 [label = "b"]
}''')
a
Out[5]:
%3 I0 0 0 I0->0 ⟨2⟩ F0 0->F0 ⟨2⟩ 1 1 0->1 a 1->0 b
In [6]: 
assert(not a.is_standard())
assert(a.standard().is_standard())