91.  S > aSabSbab; The language generated by the above grammar over the alphabet {a,b} is the set of 
a.  All palindromes 
b.  All odd length palindromes 
c.  Strings that begin and end with the same symbol 
d.  All even length palindromes 
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Answer: (b).All odd length palindromes

92.  Consider the below question: 
a.  Not recursive 
b.  Regular 
c.  Context free but not regular 
d.  Recursively enumerable but not context free 
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Answer: (c).Context free but not regular

93.  The language L= {0^i21^i  i≥0 } over the alphabet {0,1, 2} is: 
a.  not recursive 
b.  is recursive and is a deterministic CFL 
c.  is a regular language 
d.  is not a deterministic CFL but a CFL 
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Answer: (b).is recursive and is a deterministic CFL

94.  Consider the CFG with {S,A,B) as the nonterminal alphabet, {a,b) as the terminal alphabet, S as the start symbol and the following set of production rules
S > aB S > bA B > b A > a B > bS A > aS B > aBB A > bAA Which of the following strings is generated by the grammar? 
a.  aaaabb 
b.  aabbbb 
c.  aabbab 
d.  abbbba 
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Answer: (c).aabbab

95.  Consider the below statement: 
a.  L1 only 
b.  L3 Only 
c.  L1 and L2 
d.  L2 and L3 
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Answer: (d).L2 and L3

96.  Consider the following statements about the context free grammar
G = {S → SS, S → ab, S → ba, S → Ε} I. G is ambiguous II. G produces all strings with equal number of a’s and b’s III. G can be accepted by a deterministic PDA. Which combination below expresses all the true statements about G? 
a.  I only 
b.  I and III only 
c.  II and III only 
d.  I, II and III 
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Answer: (b).I and III only

97.  Which one of the following grammars generates the language L = {a^ib^j  i ≠ j} 
a.  A 
b.  B 
c.  C 
d.  D 
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Answer: (d).D

98.  Consider the languages:
L1 = {a^nb^nc^m  n, m > 0} L2 = {a^nb^mc^m  n, m > 0} Which one of the following statements is FALSE? 
a.  L1 ∩ L2 is a contextfree language 
b.  L1 U L2 is a contextfree language 
c.  L1 and L2 are contextfree language 
d.  L1 ∩ L2 is a context sensitive language 
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Answer: (a).L1 ∩ L2 is a contextfree language

99.  Consider the languages:
L1 = {ww^R w ∈ {0, 1}*} L2 = {w#w^R  w ∈ {0, 1}*}, where # is a special symbol L3 = {ww  w ∈ (0, 1}*) Which one of the following is TRUE? 
a.  L1 is a deterministic CFL 
b.  L2 is a deterministic CFL 
c.  L3 is a CFL, but not a deterministic CFL 
d.  L3 is a deterministic CFL 
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Answer: (b).L2 is a deterministic CFL

100.  Consider the NPDA 〈Q = {q0, q1, q2}, Σ = {0, 1}, Γ = {0, 1, ⊥}, δ, q0, ⊥, F = {q2}〉, where (as per usual convention) Q is the set of states, Σ is the input alphabet, Γ is stack alphabet, δ is the state transition function, q0 is the initial state, ⊥ is the initial stack symbol, and F is the set of accepting states, The state transition is as follows: Which one of the following sequences must follow the string 101100 so that the overall string is accepted by the automaton? 
a.  10110 
b.  10010 
c.  01010 
d.  01001 
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Answer: (b).10010
