automaton.ambiguous_word

Return an ambiguous word, or raise if the automaton is unambiguous.

Preconditions:

• the labelset is free

Postconditions:

• the Result is accepted

See also:

• automaton.is_ambiguous

Examples

import vcsn
a = vcsn.context('lal_char(abcd), b').expression('abc').standard()
a

a.is_ambiguous()

False

try:
    a.ambiguous_word()
except RuntimeError as err:
    print("error:", err)

error: automaton is unambiguous

a = a + a
a

a.ambiguous_word()

$\mathit{abc}$