CS2321 Exam 2 Study Guide

Suppose A = {a,b,c,d} and B = {a,d,t,f}

What is the intersection of

R1 = {(a,a), (c,d), (a,d)} and R2 = {(a,t), (a,d), (t,f)}

• {(a,b), (a,t),(c,t)}

• {(a,d)}

• Empty Set

• {a,d}

Suppose A = {a,b,c,d} and B = {a,d,t,f}

What is the union of

R1 = {(a,a), (c,d), (a,d)} and R2 = {(a,t), (a,d), (t,f)}

• {(a,a), (c,d), (a,d), (a,t),(t,f)}

• {(a,d)}

• Empty Set

• {a,b,c,d,t,f}

Suppose A = {a,b,c,d} and B = {a,d,t,f}

And

R1 = {(a,a), (c,d), (a,d)} and R2 = {(a,t), (a,d), (t,f)}

What is R1 - R2?

• {(a,t), (t,f)}

• {a,a,c,d}

• Empty Set

• {(a,a), (c,d)}

Suppose A = {a,b,c,d} and B = {a,d,t,f}

And

R1 = {(a,a), (c,d), (a,d)} and R2 = {(a,t), (a,d), (t,f)}

What is R2 - R1?

• {(a,t), (t,f)}

• {a,d,t,f}

• Empty Set

• {(a,a), (c,d)}

What is reflexive closure of

R = {(1,3), (4,2)}

• Empty Set

• {(1,3), (4,2)}

• {(1,1), (2,2), (3,3) ,(4,4)}

• {(1,1), (2,2), (1,3), (3,3) ,(4,2),(4,4)}

What is diagonal relation of

R = {(1,3), (4,2)}

• Empty Set

• {(1,3), (4,2)}

• {(1,1), (2,2), (3,3) ,(4,4)}

• {(1,1), (2,2), (1,3), (3,3) ,(4,2),(4,4)}

When finding the symmetric closure of a relation R, what is the first step?

• Cry

What is the symmetric closure of

R = {(1,2), (2,3)}

• {(1,2), (2,3), (1,3)}

• {1,2,3,4}

• Empty Set

• {(1,2), (2,3), (2,1), (3,2)}

What is the transitive closure of

R = {(1,2), (2,3)}

• {(1,2), (2,3), (1,3)}

• {1,2,3,4}

• Empty Set

• {(1,2), (2,3), (2,1), (3,2)}