CMPS 211 Homework Assignment 03 Solution, Fall 2014

American University of Beirut · Discrete Structures · 5 pages · with solution

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CMPS 211 – Fall 2014 Assignment 3 Solution Exercise 1: a) All of the professors are philosophy professors and understand logic b) There exist a professor that is a philosophy professor and understand logic c) All philosophy professors understand logic d) There exist a philosophy professor that understand logic Exercise 2: a) ∃x(I(x) ∧ S(x) ∧ N(x)) b) ¬∃x(I(x) ∧ S(x) ∧ N(x)) ≡ ∀x(¬I(x) ∨ ¬S(x) ∨ ¬N(x)) c) ∀x(I(x) ∨ S(x) ∨ N(x)) d) ∃x(I(x) ∧ ¬S(x) ∧ N(x)) e) ¬∃x(I(x) ∨ S(x) ∨ N(x)) ≡ ∀x(¬I(x) ∧ ¬S(x) ∧ ¬N(x)) Exercise 3: a) P(2): 3>3 => False b) P(3): 7>5 => True c) P(0): -­‐5>-­‐1 => False d) ∃x P(x): True (for x=3 P(3) is true) e) ∃x ¬P(x): True (for x=0 p(0) is false) f) ∀x P(x): False (for x=2 p(2) is false) g) ∀x ¬P(x): False (for x=3 P(3) is true) Exercise 4: a) P(-­‐4) ∨ P(-­‐2) ∨ P(-­‐1) ∨ P(1) ∨ P(2) ∨ P(4) b) P(-­‐4) ∧ P(-­‐2) ∧ P(-­‐1) ∧ P(1) ∧ P(2) ∧ P(4) c) ((-­‐4≠3) -­‐-­‐> P(-­‐4)) ∧ ((-­‐2≠3) -­‐-­‐> P(-­‐2)) ∧ ((-­‐1≠3) -­‐-­‐> P(-­‐1)) ∧ ((4≠3) -­‐-­‐> P(4)) ∧ ((2≠3) -­‐-­‐> P(2)) ∧ ((1≠3) -­‐-­‐> P(1)) d) (-­‐4≥1∧P(-­‐4))∨(-­‐2≥1∧P(-­‐2))∨(-­‐1≥1∧P(-­‐1))∨(4≥1∧P(4))∨(2≥1∧P(2)) ∨(1≥1∧P(1)) CMPS 211 – Fall 2014 e) (¬P(-­‐4)∨¬P(-­‐2)∨¬P(-­‐1)∨¬P(1)∨¬P(2)∨¬P(4))∧[(-­‐4<0 -­‐-­‐>P(-­‐4)∧(-­‐2<0 -­‐-­‐> P(-­‐2)∧(-­‐1<0 -­‐-­‐> P(-­‐1)∧ (4<0 -­‐-­‐>P(4)∧(2<0 -­‐-­‐> P(2)∧(1<0 -­‐-­‐> P(1)] Exercise 5: Let C(x) be x is in my classroom The domain of x is all students in my class The domain of y is all people a) Let D(x) be x can drive 1. ∃x(¬D(x)) 2. ∃y(C(y) ∧ ¬D(y)) b) Let N(x) be x has a notebook 1. ∀x(N(x)) 2. ∀y(C(y) → N(y)) c) Let R(x) be x is repeating this course 1. ∃x(R(x)) 2. ∃y(C(y) ∧ R(y)) d) Let F(x) be x can solve Fermat’s last theorem 1. ∀x(F(x)) 2. ∀y(C(y) → F(y)) e) Let W(x) be x wants to be rich 1. ∃x(¬W(x)) 2. ∃y(C(y) ∧ ¬W(y)) Exercise 6: a) There exist a CMPS professor that taught a CMPS course b) There exists a CMPS professor that taught all CMPS courses c) All CMPS professors taught a CMPS course CMPS 211 – Fall 2014 d) There exists a CMPS course that has been taught by all CMPS professors e) All CMPS courses has been taught by CMPS professors f) All CMPS professors taught all CMPS courses Exercise 7: a) Tarek Haddad is enrolled in CMPS 211 b) There exists a student in my school that is enrolled in Bio 210 c) There exists a class in my school that David Cook is enrolled in d) There exists a student that is enrolled in Math 201 and in CMPS 211 e) There exists two different students such that if the first one is enrolled in any course, then the second one is enrolled in the same course f) There exists two different students that are both enrolled in the same class or none of them is enrolled in it Exercise 8: a) ∀x ∀y ¬Q(x, y) b) ∃x ∃y Q(x, y) c) ∃x (Q(x, AMC) ∧ Q(x, IEEE)) d) ∀y ∃x Q(x, y) e) ∃x1 ∃x2 (Q(x1, IEEE) ∧ Q(x2, IEEE)) Exercise 9: The domain of x is “the students in this class” for [a-­‐g] a) Let S(x, y) be x can speak y The domain of y is “languages” ∃x S(x, Aramaic) b) Let E(x, y) be x has eaten y The domain of y is “fruits” ∃x (E(x, pears) ∧ ¬E(x, peaches)) CMPS 211 – Fall 2014 c) Let I(x, y) be x plays y The domain of y is “instruments” ∀x ∃y I(x, y) d) Let L(x, y) be x learned y The domain of y is “programing languages” ∀x ∃y L(x, y) e) Let G(x, y) be x can speak y The domain of y is “towns” ∃x1 ∃x2 ∃y (G(x1, y) ∧ G(x2, y)) f) Let B(x, y, z) be x has eaten y in z The domain of y is “dishes offered” The domain of z is “restaurants on Bliss Street” ∃x ∀y ∃z B(x, y, z) g) Let P(x, y, z) be x has played with y in game z The domain of x and y is “Lebanese soccer players” The domain of z is the “games that has been played” ∀x ∀y ∃z P(x, y, z) Exercise 10: The domain of x is “the students in this class” a) Let S(x, y) be x failed y The domain of y is “courses” ∃x ∀y ¬S(x, y) Negation: ∀x ∃y S(x, y) All of the students in this class have failed a course b) Let L(x, y) be x likes y The domain of y is “majors” CMPS 211 – Fall 2014 ∀x L(x, CMPS) Negation: ∃x ¬L(x, CMPS) There exist some students in this class who hate CMPS c) Let M(x, y) be x has taken y The domain of y is “mathematics courses offered in this school” ∃x ∀y M(x, y) Negation: ∀x ∃y ¬M(x, y) All of the students in this class have not taken mathematics courses offered by this school d) Let B(x, y, z) be x has been in y of z The domain of y is “rooms of buildings” The domain of z is “buildings in Beirut” ∃x ∃y ∀z B(x, y, z) Negation: ∀x ∀y ∃z ¬B(x, y, z) All the students in this class have not been in every room in at least one building in Beirut