Consider the nondeterministic FSM NFSM = of Figure 10.52, where S = {A,B,C,D,E, F,G} is the set of states, I = {ri,

a, c, x, z}

is the set of inputs, O = {null,

b, f, d} is the set of outputs, A is the initial state, δ : S × I → S is the next-state function, and λ : S × I → O is the output function. NFSM is nondeterministic means that for some input ak ∈ I there are more than one transitions with different outputs defined for some state.

(a) Generate UIO sequence(s) for each state of the NFSM, if those exist.

(b) Do you think the generated UIO sequences can uniquely identify the states?

Justify your answer.

(c) Devise a methodology to uniquely identify the states of the NFSM. (Hint:

The tree structure will identify the state of the NFSM uniquely.) Using your methodology, generate UIO trees for each state of the NFSM.

(d) Generate test cases for the following transitions:

(a) (F,G, x/d), (b)

(B,C, c/d), and

(c) (A,B, a/b).

(e) Represent the following two test cases in TTCN-3 form with verdicts:

(B,C, c/d) and (A,B, a/b).