There seem to be at least 2 issues in the Automaton.process method, which
is found in sage.combinat.finite_state_machine. They appear in Sage 10.3.
Unexpected errors are thrown and incorrect outputs result from calling
Automaton.process() when, in various combinations (a) instances of
FSMTransition are declared by the label of an FSMState rather than by the
instance of FSMState itself, (b) the input tape for processing is
encapsulated in a tuple, rather than a list, and (c) the inputs contain
commas, e.g. if the alphabet contains tuples. The documentation suggests
that (a) and (b) should make no difference, and makes no mention of any
issues with (c).
For instance:
from sage.combinat.finite_state_machine import FSMTransition, Automaton,
FSMState
#Test 1
my_state = FSMState(1)
my_transition = FSMTransition(1, 1, ('a','a'))
my_automaton = Automaton([my_transition], initial_states = [my_state])
my_automaton.process([('a','a')])
#throws a ValueError with message "State 1 does not belong to a finite
state machine"
#Test 2
my_state = FSMState(1)
my_transition = FSMTransition(1, 1, ('a','a'))
my_automaton = Automaton([my_transition], initial_states = [my_state])
my_automaton.process((('a','a')))
#returns the incorrect output (False, None), which indicates that (‘a’,
‘a’) was not the label of a transition starting at the initial state.
Expected output is (False, 1).
#Test 3
my_state = FSMState(1)
my_transition = FSMTransition(my_state, my_state, ('a','a'))
my_automaton = Automaton([my_transition], initial_states = [my_state])
my_automaton.process([('a','a')])
#returns the expected output (False, 1)
#Test 4
my_state = FSMState(1)
my_transition = FSMTransition(my_state, my_state, ('a','a'))
my_automaton = Automaton([my_transition], initial_states = [my_state])
my_automaton.process((('a','a')))
#returns the incorrect output (False, None), which indicates that (‘a’,
‘a’) was not the label of a transition starting at the initial state.
Expected output is (False, 1).
#Test 5
my_state = FSMState(1)
my_transition = FSMTransition(1, 1, ('a'))
my_automaton = Automaton([my_transition], initial_states = [my_state])
my_automaton.process(['a'])
#throws a ValueError with message "State 1 does not belong to a finite
state machine"
#Test 6
my_state = FSMState(1)
my_transition = FSMTransition(1, 1, 'a')
my_automaton = Automaton([my_transition], initial_states = [my_state])
my_automaton.process(('a'))
#throws a ValueError with message "State 1 does not belong to a finite
state machine"
#Test 7
my_state = FSMState(1)
my_transition = FSMTransition(my_state, my_state, 'a')
my_automaton = Automaton([my_transition], initial_states = [my_state])
my_automaton.process(['a'])
#returns the expected output (False, 1)
#Test 8
my_state = FSMState(1)
my_transition = FSMTransition(my_state, my_state, 'a')
my_automaton = Automaton([my_transition], initial_states = [my_state])
my_automaton.process(('a'))
#returns the expected output (False, 1)
My best guess is that these bugs have to do with the way FSMStates are
assigned the .transitions attribute. In other tests, calling
Automaton.process has thrown AttributeErrors in lines that ask for this
attribute.
Best,
Daniel Levitin
P.S. I would be happy to try to fix this myself, but I do not understand
the way the process iterator works. If someone here is familiar with this
module and is willing to explain it to me, I would appreciate it.
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