Explore topic-wise MCQs in Control Systems.

This section includes 233 Mcqs, each offering curated multiple-choice questions to sharpen your Control Systems knowledge and support exam preparation. Choose a topic below to get started.

1.

Consider the translation scheme shown belowS → T RR → + T {print ('+');} R | εT → num {print (num.val);}Here num is a token that represents an integer and num.val represents thecorresponding integer value. For an input string '9 + 5 + 2', this translation scheme willprint

A. 9 + 5 + 2
B. 9 5 + 2 +
C. 9 5 2 + +
D. + + 9 5 2
Answer» C. 9 5 2 + +
Discussion
2.

Consider the following two statements:S1: { 0^2n |n >= l} is a regu1ar languageS2: { 0^m 0^n 0^(m+n) l m >= 1 and n >= 2} is a regu1ar languageWhich of the following statements is correct?

A. Only S1 is correct
B. Only S2 is correct
C. Both S1 and S2 are correct
D. None of S1 and S2 is correct
Answer» D. None of S1 and S2 is correct
Discussion
3.

Consider the intermediate code given below:1. i = 12. j = 13. t1 = 5 * i4. t2 = t1 + j5. t3 = 4 * t26. t4 = t37. a[t4] = –18. j = j + 19. if j

A. 5 and 7
B. 6 and 7
C. 5 and 5
D. 7 and 8
Answer» C. 5 and 5
Discussion
4.

Consider the following statements about the context free grammarG = {S - >SS, S - >ab, S - >ba, S - ε}I. G is ambiguousII. G produces all strings with equal number of a’s and b’sIII. G can be accepted by a deterministic PDA.Which combination below expresses all the true statements about G?

A. 1 only
B. 1 and 3
C. 2 and 3
D. 1,2 and 3
Answer» E.
Discussion
5.

The expression (a*b)* c op........ where 'op' is one of '+', '*' and '↑' (exponentiation) can be evaluated on a CPU with a single register without storing the value of (a * b) if

A. ‘op’ is ‘+’ or ‘*’
B. 'op’ is ‘↑’ or ‘*’
C. 'op’ is ‘↑’ or ‘+’
D. not possible to evaluate without storing
Answer» B. 'op’ is ‘↑’ or ‘*’
Discussion
6.

For S € (0+1)* let d(s)denote the decimal value of s(e.g.d(101)= 5).Let L = {s € (0 + 1) | d (s) mod 5 = 2 and d (s) mod 7 != 4)}Which one of the following statements is true?

A. L is recursively enumerable, but not recursive
B. L is recursive, but not context-free
C. L is context-free, but not regular
D. L is regular
Answer» E.
Discussion
7.

Consider the following statements related to compiler construction : I. Lexical Analysis is specified by context-free grammars and implemented by pushdown automata. II. Syntax Analysis is specified by regular expressions and implemented by finite-state machine. Which of the above statement(s) is/are correct?

A. Only I
B. Only II
C. Both I and II
D. Neither I nor II
Answer» E.
Discussion
8.

Consider the following two problems on undirected graphs:α: Given G(V,E), does G have an independent set of size |v|—4?β: Given G(V,E), does G have an independent set of size 5?Which one of the following is TRUE?

A. α is in P and β is NP-complete
B. α is NP complete and β is in P
C. Both α and β are NP-complete
D. Both α and β are in P
Answer» C. Both α and β are NP-complete
Discussion
9.

Consider the regular language L =(111+11111)*. The minimum number of states

A. 3
B. 5
C. 8
D. 9
Answer» E.
Discussion
10.

Assume that the SLR parser for a grammar G has n1 states and the LALR parser for G has n2 states. The relationship between n1 and n2 is:

A. n1 is necessarily less than n2
B. n1 is necessarily equal to n2
C. n1 is necessarily greater than n2
D. none of these
Answer» C. n1 is necessarily greater than n2
Discussion
11.

Consider the grammar with the following translation rules and E as the start symbol.E → E1 # T { E.value = E1.value * T.value } | T{ E.value = T.value }T → T1 & F { T.value = T1.value + F.value } | F{ T.value = F.value }F → num { F.value = num.value }Compute E.value for the root of the parse tree for the expression: 2 # 3 & 5 # 6 & 4.

A. 200
B. 180
C. 160
D. 40
Answer» D. 40
Discussion
12.

Consider the following C code segment.for (i = 0, i

A. The code contains loop invariant computation
B. There is scope of common sub-expression elimination in this code
C. There is scope of strength reduction in this code
D. There is scope of dead code elimination in this code
Answer» E.
Discussion
13.

The number of tokens in the following C statement is (GATE 2000)printf("i = %d, &i = %x", i, &i);

A. 3
B. 26
C. 10
D. 21
Answer» D. 21
Discussion
14.

Consider the following identities for regular expressions: (a) (r + s)* = (s + r)* (b) (r*)* = r* (c) (r* s*)* = (r + s)* Which of the above identities are true?

A. (a) and (b) only
B. (b) and (c) only
C. (c) and (a) only
D. (a), (b) and (c)
Answer» E.
Discussion
15.

Consider the following grammar:S → FRR → S | εF → idIn the predictive parser table, M, of the grammar the entries M[S, id] and M[R, $]respectively.

A. {S → FR} and {R → ε }
B. {S → FR} and { }
C. {S → FR} and {R → *S}
D. {F → id} and {R → ε}
Answer» B. {S → FR} and { }
Discussion
16.

Let L={w \in (0 + 1)*|w has even number of 1s}, i.e. L is the set of all bit strings with even number of 1s. Which one of the regular expression below represents L?

A. (0*10*1)*
B. 0*(10*10*)*
C. 0*(10*1*)*0*
D. 0*1(10*1)*10*
Answer» C. 0*(10*1*)*0*
Discussion
17.

Which of the following is essential for converting an infix expression to the postfix from efficiently?

A. An operator stack
B. An operand stack
C. An operand stack and an operator stack
D. A parse tree
Answer» B. An operand stack
Discussion
18.

The regular grammar for the language L = {anbm | n + m is even} is given by

A. S → S1 | S2 S1 → a S1| A1 A1 → b A1| λ S2 → aaS2| A2 A2 → b A2| λ
B. S → S1 | S2 S1 → a S1| aA1 S2 → aaS2| A2 A1 → b A1| λ A2 → b A2| λ
C. S → S1 | S2 S1 → aaa S1| aA1 S2 → aaS2| A2 A1 → b A1| λ A2 → b A2| λ
D. S → S1 | S2 S1 → aa S1| A1 S2 → aaS2| A2 A1 → bb A1| λ A2 → bb A2| λ
Answer» E.
Discussion
19.

Which of the following problems are decidable?1) Does a given program ever produce an output?2) If L is a context-free language, then is L’ (complement of L) also context-free?3) If L is a regular language, then is L’ also regular?4) If L is a recursive language, then, is L’ also recursive?

A. 1, 2, 3, 4
B. 1, 2
C. 2, 3, 4
D. 3, 4
Answer» E.
Discussion
20.

The grammar A → AA | (A) | ε is not suitable for predictive-parsing because thegrammar is

A. ambiguous
B. left-recursive
C. right-recursive
D. an operator-grammar
Answer» B. left-recursive
Discussion
21.

Which of the following grammar rules violate the requirements of an operator grammar ? P, Q, R are nonterminals, and r, s, t are terminals.1. P → Q R2. P → Q s R3. P → ε4. P → Q t R r

A. 1 only
B. 1 and 3 only
C. 2 and 3 only
D. 3 and 4 only
Answer» C. 2 and 3 only
Discussion
22.

If s is a string over (0 + 1)* then let n0 (s) denote the number of 0’s in s and n1 (s)the number of l’s in s. Which one of the following languages is not regular?

A. L = {s € (0 + 1)*n0 (s) is a 3-digit prime
B. L = {s € (0 + 1)* | for every prefix s’ of s, l 0 (s’) — n1 (s’) | <= 2 }
C. L={s € (0+1)* | n0(s) - n1(s) | <= 4}
D. L = {s € (0 + 1) | n0 (s) mod 7 = n1 (s) mod 5 = 0 }
Answer» D. L = {s € (0 + 1) | n0 (s) mod 7 = n1 (s) mod 5 = 0 }
Discussion
23.

Consider the language L1,L2,L3 as given below. L1={0^{p}1^{q} | p,q \in N}L2={0^{p}1^{q} | p,q \in N and p=q} L3={0^{p}1^{q}1^{r} | p,q,r \in N and p=q=r}Which of the following statements is NOT TRUE?

A. Push Down Automata (PDA) can be used to recognize L1 and L2
B. L1 is a regular language
C. All the three languages are context free
D. Turing machine can be used to recognize all the three languages
Answer» D. Turing machine can be used to recognize all the three languages
Discussion
24.

Given an arbitrary non-deterministic finite automaton (NFA) with N states, the maximum number of states in an equivalent minimized DFA is at least.

A. N^2
B. 2^N
C. 2N
D. N!
Answer» C. 2N
Discussion
25.

Which of the following are decidable?I. Whether the intersection of two regular languages is infiniteII. Whether a given context-free language is regularIII. Whether two push-down automata accept the same languageIV. Whether a given grammar is context-free

A. I and II
B. I and IV
C. II and III
D. II and IV
Answer» C. II and III
Discussion
26.

Let L denotes the language generated by the grammar S – OSO/00. Which of the following is true?

A. L = O
B. L is regular but not O
C. L is context free but not regular
D. L is not context free
Answer» C. L is context free but not regular
Discussion
27.

A linker reads four modules whose lengths are 200, 800, 600 and 500 words respectively. If they are loaded in that order, what are the relocation constants?

A. 0, 200, 500, 600
B. 0, 200, 1000, 1600
C. 200, 500, 600, 800
D. 200, 700, 1300, 2100
Answer» C. 200, 500, 600, 800
Discussion
28.

Which of the following statements in true?

A. If a language is context free it can always be accepted by a deterministic push-down automaton
B. The union of two context free languages is context free
C. The intersection of two context free languages is context free
D. The complement of a context free language is context free
Answer» C. The intersection of two context free languages is context free
Discussion
29.

Which of the following languages is regular?

A. {WW^R | W € {0,1}+ }
B. {WW^R X | X W € {0,1}+ }
C. {WW^R | X W € {0,1}+ }
D. {XWW^R | X W € {0,1}+ }
Answer» D. {XWW^R | X W € {0,1}+ }
Discussion
30.

A language L allows declaration of arrays whose sizes are not known during compilation. It is required to make efficient use of memory. Which of the following is true?

A. A compiler using static memory allocation can be written for L
B. A compiler cannot be written for L, an interpreter must be used
C. A compiler using dynamic memory allocation can be written for L
D. None of the above
Answer» D. None of the above
Discussion
31.

Consider the following translation scheme. S → ER R → *E{print("*");}R | ε E→ F + E {print("+");} | F F → (S) | id {print(id.value);} Here id is a token that represents an integer and id.value represents the corresponding integer value. For an input '2 * 3 + 4', this translation scheme prints

A. 2 * 3 + 4
B. 2 * +3 4
C. 2 3 * 4 +
D. 2 3 4+*
Answer» E.
Discussion
32.

Let L = L1 \cap L2, where L1 and L2 are languages as defined below: L1 = {a^{m}b^{m}ca^{n}b^{n} | m, n >= 0 } L2 = {a^{i}b^{j}c^{k} | i, j, k >= 0 } Then L is

A. Not recursive
B. Regular
C. Context free but not regular
D. Recursively enumerable but not context free.
Answer» D. Recursively enumerable but not context free.
Discussion
33.

Consider the grammar shown below S → i E t S S' | a S' → e S | ε E → b In the predictive parse table. M, of this grammar, the entries M[S', e] and M[S', $] respectively are

A. {S' → e S} and {S' → e}
B. {S' → e S} and {}
C. {S' → ε} and {S' → ε}
D. {S' → e S, S'→ ε} and {S' → ε}
Answer» E.
Discussion
34.

Consider the following grammar.S -> S * ES -> EE -> F + EE -> FF -> idConsider the following LR(0) items corresponding to the grammar above.(i) S -> S * .E(ii) E -> F. + E(iii) E -> F + .EGiven the items above, which two of them will appear in the same set in the canonicalsets-of-items for the grammar?

A. (i) and (ii)
B. (ii) and (iii)
C. (i) and (iii)
D. None of the above
Answer» E.
Discussion
35.

A minimum state deterministic finite automation accepting the language L = {W |W € {0,1}* , number of 0's and 1's in W are divisible by 3 and 5 respectively has

A. 15 States
B. 11 states
C. 10 states
D. 9 states
Answer» B. 11 states
Discussion
36.

Consider the following context free languages:L1 = {0^i 1^j 2^k | i+j = k}L2 = {0^i 1^j 2^k | i = j or j = k}L3 = {0^i 1^j | i = 2j+1}Which of the following option is true?

A. L1, L2 and L3 can be recognized by Deterministic Push down automata
B. L1, L2 can be recognized by Deterministic Push down automata
C. L1, L3 can be recognized by Deterministic Push down automata
D. None of the above
Answer» D. None of the above
Discussion
37.

Consider the following two statements:P: Every regular grammar is LL(1)Q: Every regular set has a LR(1) grammarWhich of the following is TRUE?

A. Both P and Q are true
B. P is true and Q is false
C. P is false and Q is true
D. Both P and Q are false
Answer» D. Both P and Q are false
Discussion
38.

Which is True about SR and RR-conflict:

A. If there is no SR-conflict in CLR(1) then definitely there will be no SR-conflict in LALR(1).
B. RR-conflict might occur if lookahead for final items(reduce-moves) is same.
C. Known that CLR(1) has no RR-conflict, still RR-conflict might occur in LALR(1).
D. All of the above.
Answer» E.
Discussion
39.

Definition of a language L with alphabet {a} is given as following. L= { a^{nk} | k > 0, and n is a positive integer constant} What is the minimum number of states needed in a DFA to recognize L?

A. k+1
B. n+1
C. 2^(n+1)
D. 2^(k+1)
Answer» C. 2^(n+1)
Discussion
40.

Let be the encoding of a Turing machine as a string over ∑= {0, 1}. Let L = { |M is a Turing machine that accepts a string of length 2014 }. Then, L is

A. decidable and recursively enumerable
B. undecidable but recursively enumerable
C. undecidable and not recursively enumerable
D. decidable but not recursively enumerable
Answer» C. undecidable and not recursively enumerable
Discussion
41.

An LALR(1) parser for a grammar G can have shift-reduce (S-R) conflicts if andonly if

A. the SLR(1) parser for G has S-R conflicts
B. the LR(1) parser for G has S-R conflicts
C. the LR(0) parser for G has S-R conflicts
D. the LALR(1) parser for G has reduce-reduce conflicts
Answer» C. the LR(0) parser for G has S-R conflicts
Discussion
42.

Consider the set of strings on {0,1} in which, every substring of 3 symbols has at most two zeros. For examples, 001110 and 011001 are in the language, but 100010 is not. All strings of length less than 3 are also in the language. A partially completed DFA that accepts this language is shown below. The missing arcs in the DFA are

A. A
B. B
C. C
D. D
Answer» E.
Discussion
43.

Consider the following code segment.x = u - t;y = x * v;x = y + w;y = t - z;y = x * y;The minimum number of total variables required to convert the above code segment tostatic single assignment form is Note : This question was asked as Numerical AnswerType.

A. 6
B. 8
C. 9
D. 10
Answer» E.
Discussion
44.

Consider the following two sets of LR(1) items of an LR(1) grammar. X -> c.X, c/d X -> .cX, c/d X -> .d, c/d X -> c.X, $ X -> .cX, $ X -> .d, $Which of the following statements related to merging of the two sets in thecorresponding LALR parser is/are FALSE?1. Cannot be merged since look aheads are different.2. Can be merged but will result in S-R conflict.3. Can be merged but will result in R-R conflict.4. Cannot be merged since goto on c will lead to two different sets.

A. 1 only
B. 2 only
C. 1 and 4 only
D. 1, 2, 3, and 4
Answer» E.
Discussion
45.

S –> aSa| bSb| a| b ;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.
Answer» C. Strings that begin and end with the same symbol
Discussion
46.

Consider the following expression grammar. The seman-tic rules for expressioncalculation are stated next to each grammar production.E → number E.val = number. val | E '+' E E(1).val = E(2).val + E(3).val | E '×' E E(1).val = E(2).val × E(3).valThe above grammar and the semantic rules are fed to a yacc tool (which is an LALR (1)parser generator) for parsing and evaluating arithmetic expressions. Which one of thefollowing is true about the action of yacc for the given grammar?

A. It detects recursion and eliminates recursion
B. It detects reduce-reduce conflict, and resolves
C. It detects shift-reduce conflict, and resolves the conflict in favor of a shift over a reduce action
D. It detects shift-reduce conflict, and resolves the conflict in favor of a reduce over a shift action
Answer» D. It detects shift-reduce conflict, and resolves the conflict in favor of a reduce over a shift action
Discussion
47.

A canonical set of items is given belowS --> L. > RQ --> R.On input symbol < the set has

A. a shift-reduce conflict and a reduce-reduce conflict.
B. a shift-reduce conflict but not a reduce-reduce conflict.
C. a reduce-reduce conflict but not a shift-reduce conflict.
D. neither a shift-reduce nor a reduce-reduce conflict.
Answer» E.
Discussion
48.

For S ∈ (0 + 1) * let d(s) denote the decimal value of s (e.g. d(101) = 5). Let L = {s ∈ (0 + 1)* d(s)mod5 = 2 and d(s)mod7 != 4}. Which one of the following statements is true?

A. L is recursively enumerable, but not recursive
B. L is recursive, but not context-free
C. L is context-free, but not regular
D. L is regular
Answer» E.
Discussion
49.

Match all items in Group 1 with correct options from those given in Group 2.List I List IIP. Regular Expression 1. Syntax analysisQ. Push down automata 2. Code GenerationR. Dataflow analysis 3. Lexical analysisS. Register allocation 4. Code optimization

A. P-4. Q-1, R-2, S-3
B. P-3, Q-1, R-4, S-2
C. P-3, Q-4, R-1, S-2
D. P-2, Q-1, R-4, S-3
Answer» C. P-3, Q-4, R-1, S-2
Discussion
50.

Consider the following expressionu*v+a-b*c Which one of the following corresponds to a static single assignment from the above expressions

A. x1 = a - b y1 = p * c x2 = u * v y2 = p + q
B. x 1 = a - b y1 = x2 * c x3 = u * v y2 = x4 + y3
C. x1 = a - b y2 = x1 * c x2 = u * v y3 = x2 + y2
D. p = a - b q = p * c p = u * v q = p + q
Answer» D. p = a - b q = p * c p = u * v q = p + q
Discussion