Let R be a relation on the set of all integers such that aRb if
and only if 3a − 5b is even. Tell if R is an equivalence relation.
Justify your answer. (Hint: 3b − 5a = 3a − 5b + 8b − 8a)
Let R be the following relation on the set of all alive people
in the world:
x R y if and only if x and y have the same pair of biological
parents.
Prove that R is an equivalence relation.
Let R be a relation on a set that is reflexive and symmetric but
not transitive? Let R(x) = {y : x R y}. [Note that R(x) is the same
as x / R except that R is not an equivalence relation in this
case.] Does the set A = {R(x) : x ∈ A} always/sometimes/never form
a partition of A? Prove that your answer is correct. Do not prove
by examples.
Show that the given relation R is an equivalence relation on set
S. Then describe the equivalence class containing the given element
z in S, and determine the number of distinct equivalence classes of
R.
Let S be the set of all possible strings of 3 or 4 letters, let
z = ABCD and define x R y to mean that x has the same first letter
as y and also the same third letter as y.
Question: Consider the relation R on A defined by aRb iff 1mod4
= bmod4
a)Construct the diagraph for this relation
b)show that R is an equivalence relation
Part B: Now consider the relation R on A defined by aRb iff a
divides b (Divides relation)
c) Show that R is partial ordering
d) Contruct the hasse diagram for this relation
let
G be a simple graph. show that the relation R on the set of
vertices of G such that URV if and only if there is an edge
associated with (u,v) is a symmetric irreflexive relation on
G
Suppose we define the relation R on the set of all people by the
rule "a R b if and only if a is Facebook friends with b."
Is this relation reflexive? Is is symmetric? Is it transitive?
Is it an equivalence relation?
Briefly but clearly justify your answers.
Determine whether the relation R on the set of all
people is reflexive, symmetric, antisymmetric, and/or transitive,
where (a, b) ∈ R if and only if
a) a is taller than b.
b) a and b were born on the same day.