1. Which of the following statement is incorrect? (a) The e-closure of a state can be found by following all paths out of the state that are composed of empty strings. (b) An e-NFA may be converted to a DFA. (c) A language accepted by some e-NFA if and only if the language is accepted by some DFA. (d) Some e-NFA's have no equivalent DFA's.

2. Which of the following statements is incorrect?     (a) It is appropriate to use finite automata for searching text in documents. (b) A DFA may be regarded as a special case of NFA. (c) We can implement an NFA by converting it to a DFA and writing a simulation program. (d) Sometimes An NFA cannot be converted to a DFA.

3. Which of the following statements is incorrect? (a) An empty string may be accepted by a specially-designed e-NFA. (b) The function of a digital lock may be modeled by an NFA. (c) Computing models are said to be equivalent if their languages are identical.(d) A DFA is a generator of languages.

4. Which of the following statements is incorrect? (a) Finite automata can be used for text search.(b) Inverted indexing is a technique for text search.(c) Text search is a form of finding strings of symbols in documents.(d) Inverted indexing can be used for searching documents which change rapidly.

5. Which of the following statements is incorrect?(a) An e-NFA is a nondeterministic FA with e-transitions.(b) An e-transition is a state transition taking an empty string e as input.(c) An e-NFA is more intuitive for use in automata design.(d) An e-NFA is more powerful than an NFA without e-transitions in language modeling.