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 sys
import vcsn
a = vcsn.B.expression('abc').standard()
a

a.is_ambiguous()

False

try:
    a.ambiguous_word()
except RuntimeError as err:
    print("error:", err, file=sys.stderr)

error: ambiguous_word: automaton is unambiguous

a = vcsn.B.expression('in (xxyy + xx + yy)* out').automaton()
a

a.ambiguous_word()

$\mathit{inxxyyout}$