FiniteStateMachine.composition: check types

[cheuberg]

The output of an automaton should not be feedable into a transducer (because there is none); when composing an automaton with a transducer, the result should be an automaton.

The aim would be:

sage: from sage.combinat.finite_state_machine import (
....:     is_Automaton, is_Transducer)
sage: T = Transducer([(0, 0, 0, 0)], initial_states=[0])
sage: A = Automaton([(0, 0, 0)], initial_states=[0])
sage: T.composition(A, algorithm='direct')
Traceback (most recent call last):
...
TypeError: Composition with automaton is not possible.
sage: T.composition(A, algorithm='explorative')
Traceback (most recent call last):
...
TypeError: Composition with automaton is not possible.
sage: A.composition(A, algorithm='direct')
Traceback (most recent call last):
...
TypeError: Composition with automaton is not possible.
sage: A.composition(A, algorithm='explorative')
Traceback (most recent call last):
...
TypeError: Composition with automaton is not possible.
sage: is_Automaton(A.composition(T, algorithm='direct'))
True
sage: is_Automaton(A.composition(T, algorithm='explorative'))
True

This is now achieved by this patch.

CC: @sagetrac-skropf @dkrenn

Component: finite state machines

Keywords: composition

Author: Clemens Heuberger

Branch/Commit: 61f6acf

Reviewer: Daniel Krenn

Issue created by migration from https://trac.sagemath.org/ticket/16758

[cheuberg]

New commits:

5704b11	trac #16758: Add failing doctests
6dc0263	trac #16758: Disallow composition with automaton
61f6acf	trac #16758: Use class of outer machine in composition

[cheuberg]

Branch: u/cheuberg/fsm/composition-types

[cheuberg]

Commit: 61f6acf

[cheuberg]

Author: Clemens Heuberger

[dkrenn]

Reviewer: Daniel Krenn

[dkrenn]

comment:3

Fine for me.

[vbraun]

Changed branch from u/cheuberg/fsm/composition-types to 61f6acf