ITPEC FE Morning April 2022 Question 5
The table below shows state transition for character string inspection. During the inspection, if the state changes to E, the string under inspection is rejected. Which of the following is rejected in this inspection? Here, state A is the initial state, strings are inspected from left to right, and symbol △ indicates a blank character.
Explanation
12.2 — after a radix point the inspection is in state D, and a number in state D leads to E.
Trace each string from state A, one character at a time:
- •(a) +0010: A →(sign) C →(0) B → B → B → B: never reaches E, accepted
- •(b) −1: A →(sign) C →(1) B: accepted
- •(c) 12.2: A →(1) B →(2) B →(.) D →(2) E: rejected
- •(d) 9.△: A →(9) B →(.) D →(blank) A: accepted
Answer (c)
Why not others:
- •(a) — a sign in state A goes to C, and every digit after that stays in B
- •(b) — a sign followed by one digit ends in B, a valid state
- •(d) — state D accepts a blank, which returns to A; only a digit, sign, radix point or other character after the point is rejected
Key rule: Trace every character, including signs and blanks, and read the next state from the row of the current state, not of the starting one.
Basic Theory · AI-written, may contain errors
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