FSM, Test Script, UIO – Computer Science Stack Exchange

I stay with it. I have the system displayed here: https://imgur.com/a/kcmf8NR

a) Find W and P (UIO)

b) Write the following two scripts with P (UIO) from the previous question:
S1 verification (1, b / y, 4)
S2 check (0, a / y, 2). (2, b / y, 1)

c) A script was run on this IUT that had the same goal as S1. The output was: zero, y, x, x, y, x, x, x
How do you interpret this issue? (FAIL, OK or INCLUDED)

d) A tester receives an error from its test and output: zero, x, x, y.
What can you derive from it?

First, I minimized the system as follows: https://imgur.com/a/5TLcjet
For a) I found the following:
w = {bb}

For S1, I did the following: RN, ay, by, bx, by
S2: RN ay, by, RN, ay, bx, bx

I think S1 is okay, but not sure about S2. I do not know how to check after the first transition if you have actually reached 2.

c) I think it's a mixed mistake. We do not get y as output before you reach the status 1. So it looks like we would choose a / x of 1 instead of b / y, which would be a transmission error + output error (ie mixed).

d) I think they tested (0, b / x, 0) and got another mixed mistake. Not sure.

Can anyone help me?