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The correct OPTION is (a) LEXEME

The best EXPLANATION: INDIVIDUAL TOKEN is also Called Lexeme.

Correct answer is (a) First

For EXPLANATION: LEXICAL Analyzer is First Phase of COMPILER.

Correct OPTION is (d) All of the mentioned

To elaborate: Lexical Analyzer is also CALLED “Linear PHASE” or “Linear ANALYSIS” or “Scanning“.

The correct choice is (b) Produces more than one PARSE TREE

The explanation: Since more than one parse tree is generated HENCE one than OPTION is AVAILABLE .Therefore it’s ambiguous.

The CORRECT choice is (d) All of the mentioned

Explanation: All these expression GIVE US a regular GRAMMAR when L1 and L2 are regular.

Correct CHOICE is (c) (a+b)* BB

For explanation: Only this EXPRESSION ends with bb only.

The CORRECT answer is (c) 1(01)* and (10)*1 & X(xx)* and (xx)*x

The best I can explain: R1 and R2 are REVERSE of each other. If ant ONE of them can be generated them the other can be generated as well.

Right option is (b) EVERY SUBSET of a RECURSIVELY enumerable set is recursive

Easiest EXPLANATION: Every subset of a recursively enumerable set is recursive.

The correct choice is (a) Scanner

To elaborate: The FIRST STAGE, the scanner, is FSM. It has ENCODED information on the POSSIBLE SEQUENCES of characters that can be contained within any of the tokens it handles.

The correct answer is (c) b*c|a

The EXPLANATION: Either b or a can lead FOLLOWED by c this expression can be ACHIEVED by C as WELL.

Correct option is (d) All of the mentioned

For explanation: JavaCC – JavaCC generates lexical ANALYZERS written in Java.

JFLex – A lexical ANALYZER GENERATOR for Java.

Quex – A fast universal lexical analyzer generator for C and C++.

FsLex – A lexer generator for byte and UNICODE character input for F#.

Correct answer is (C) B*a(a+b)*

BEST explanation: INITIALLY circle s around b so b* then a then FOLLOWED by (a+b)*.

The CORRECT answer is (a) 111001

For explanation I would say: 111001 cannot be the suffix of any string accepted by this DFA. Suppose s=w111001. No matter what state the DFA reaches after READING w, it will go to state D after reading “111”, then go to state B after reading “00” and finally reaches state C after reading “1”.

Correct choice is (a) D,C

The explanation is: The cycle of unit-productions S → A → D → S says that any PAIR INVOLVING only S, A, and D is a unit pair. Similarly, the cycle S → B → E → S tells US that any pair involving S, B, and E is a unit pair.

The CORRECT option is (b) {w ∈ {a, b}* every a in w is followed by at least TWO b’}

Explanation: We can try some SAMPLE strings like aba, abbbabbb.

Correct choice is (C) C D

The BEST I can EXPLAIN: The states traversed are ABDBDABDAC, and the only EDGE not traversed C D.

Correct choice is (a) R = QP*

Explanation: It is an IMPORTANT law primarily USED in CONVERSION.

Right OPTION is (d) WHITE Space & Comments

Best EXPLANATION: Two IMPORTANT common lexical categories are white space and comments.

The CORRECT option is (a) True

Easy EXPLANATION: NFA has n then DFA has at MAX 2^n.

Correct option is (d) 021300211 & 022111300211

The BEST explanation: First, notice that A generates strings of the FORM 021, where n is 0 or more. Also, B gives ZERO or more 1’s, which is followed by one 3, and then A gives something. Since S generates something an A can generate followed by something a B can generate, the strings in L (G) are of the form 0 21 30 21.

Correct choice is (b) 1

Easiest explanation: In DFA M: all strings MUST END with ‘a’. In DFA N: all strings must end with ‘b’. So the INTERSECTION is EMPTY. For an empty language, only one state is NEEDED.

Correct option is (c) STREAM of Token

Easy EXPLANATION: The output GIVEN is in the form of tokens.

The correct ANSWER is (a) Scanner

The explanation: In order to CONSTRUCT a token, the lexical analyzer needs a second stage, the evaluator, which GOES over the characters of the LEXEME to PRODUCE a value.

Right ANSWER is (b) 3

Explanation: baa is not REGULAR so 3.

Correct option is (d) Either L must be {an | n is ODD}, or L must be {an | n is even}

Easy EXPLANATION: There are TWO STATES. When first state is final, it accepts even no. of a’s. When second state is final, it accepts odd no. of a’s.

Correct choice is (c) String whose length is PERFECT square and consists of 0s & Palindromes consistingof 0’s and 1’s

Best explanation: STRINGS of odd numbers of zeros can be generated by regular expression (00)*0.

Right answer is (C) Integer Literal

To ELABORATE: Lexeme

Token CATEGORY

Right answer is (a) True

The BEST EXPLANATION: Lexers are often generated by a LEXER GENERATOR same as parser.

Correct OPTION is (c) Must be same

The EXPLANATION: Given any NDFA ONE can CONSTRUCT an equivalent DFA.

The correct option is (a) 0^n

The BEST I can explain: ACCORDING to pumping lemma, is not a REGULAR language. It is the language of the DFA with two states to ACHIEVE an even NUMBER of 0’s…

Right choice is (b) 2

The EXPLANATION is: STATE q0 can be omitted because it TAKES the same input as state q1 HENCE by removing q0 nothing changes.

 Following is equivalent FSA with 2 states.

The correct choice is (a) L/a is ALWAYS a REGULAR language

Explanation: We can build a DFA for as such: FIRSTLY we get the DFA for: Then, we copy all the states and transitions to the DFA for. HOWEVER, we mark any state as a final state in if and only if is a final state in.

The CORRECT CHOICE is (a) True

The EXPLANATION is: They both are EQUIVALENT.

Right OPTION is (a) SOURCE Code

To ELABORATE: Lexical ANALYSIS Identifies DIFFERENT Lexical Units in a source Code.

Correct ANSWER is (a) True

To EXPLAIN: For every NFA there is an ε-NFA that accepts a similar LANGUAGE and vice VERSA.