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Boolean Algebra and Minimization

GATE CSE 2015 Set 3 · Q44

MCQ2 marksEasy

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Given the function F=P′+QRF = P^{\prime} + QR, where FF is a function in three Boolean variables P,QP, Q and RR and P′=!PP^{\prime} = !P, consider the following statements. (S1) F=∑(4,5,6)F = \sum (4, 5, 6) (S2) F=∑(0,1,2,3,7)F = \sum (0, 1, 2, 3, 7) (S3) F=∏(4,5,6)F = \prod (4, 5, 6) (S4) F=∏(0,1,2,3,7)F = \prod (0, 1, 2, 3, 7) Which of the following is true?

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Solution

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Official answer: A) (S1)- False, (S2)- True, (S3)- True, (S4)- False

Boolean Algebra and Minimization

To express the Boolean function F(P,Q,R)=P′+QRF(P, Q, R) = P^{\prime} + QR in canonical sum-of-minterms (SOP) and product-of-maxterms (POS) forms:

  1. Expand the terms into canonical minterms:

    P′=P′(Q+Q′)(R+R′)=P′Q′R′+P′Q′R+P′QR′+P′QR=m0+m1+m2+m3P^{\prime} = P^{\prime}(Q + Q^{\prime})(R + R^{\prime}) = P^{\prime}Q^{\prime}R^{\prime} + P^{\prime}Q^{\prime}R + P^{\prime}QR^{\prime} + P^{\prime}QR = m_0 + m_1 + m_2 + m_3
    QR=(P+P′)QR=PQR+P′QR=m7+m3QR = (P + P^{\prime})QR = PQR + P^{\prime}QR = m_7 + m_3
  2. Combining these gives the minterm expansion:

    F(P,Q,R)=m0+m1+m2+m3+m7=∑(0,1,2,3,7)F(P, Q, R) = m_0 + m_1 + m_2 + m_3 + m_7 = \sum (0, 1, 2, 3, 7)

    Thus, statement (S2) is True and (S1) is False.

  3. The maxterms of FF correspond to the minterms not present in FF, which are 4,5,64, 5, 6:

    F(P,Q,R)=M4⋅M5⋅M6=∏(4,5,6)F(P, Q, R) = M_4 \cdot M_5 \cdot M_6 = \prod (4, 5, 6)

    Thus, statement (S3) is True and (S4) is False.

Hence, the correct evaluation of the statements is: (S1)- False, (S2)- True, (S3)- True, (S4)- False, which corresponds to option (A).

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This Boolean Algebra and Minimization previous year question is Q44 of the GATE CSE 2015 Set 3 paper. Find more GATE CSE PYQs on Boolean Algebra and Minimization in Digital Logic, or browse all GATE CSE PYQs.

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Boolean Algebra and Minimization in GATE CSE

Boolean Algebra and Minimization has 36 GATE CSE PYQs across 23 papers from 2011 to 2026. 9 of them are 2-mark MCQs like this one, and GATE CSE 2015 Set 3 has 3.

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GateAI solution cardGATE CSE 2015 Set 3 · Q44 · MCQ

Given the function F = P' + QR, where F is a function in three Boolean variables P, Q and R and P' = !P, consider the following statements. (S1) F = Σ (4, 5, 6) (S2) F = Σ (0, 1, 2, 3, 7) (S3) F = Π (4, 5, 6) (S4) F = Π (0, 1, 2, 3, 7) Which of the following is true?

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Independent practice explanation verified by the GateAI team. GATE is conducted by the IITs; question text follows the official paper.