Assume A = R and the relation R ⊆ A × A such that for x,...
Assume A = R and the relation R ⊆ A × A such that for x, y, ∈ R,
xRy if and only if sin2 x + cos2 y = 1. Prove that R is an
equivalence relation and for any fixed x ∈ R, find the equivalence
class x
Let A = R x R, and let a relation S be defined as: “(x1, y1)
S (x2, y2) ⬄ points (x1, y1) and (x2, y2)are 5 units
apart.” Determine whether S is reflexive, symmetric, or transitive.
If the answer is “yes,” give a justification (full proof is not
needed); if the answer is “no” you must give a
counterexample.
Consider the equation x^2+(y-2)^2 and the relation “(x, y) R (0,
2)”, where R is read as “has distance 1 of”. For example, “(0, 3) R
(0, 2)”, that is, “(0, 3) has distance 1 of (0, 2)”. This relation
can also be read as “(x, y) belongs to the circle of radius 1 with
center (0, 2)”. In other words: “(x, y) satisfies this equation if,
and only if, (x, y) R (0, 2)”. Does this equation determine a...
6. Let R be a relation on Z x Z such that for all ordered pairs
(a, b),(c, d) ∈ Z x Z, (a, b) R (c, d) ⇔ a ≤ c and b|d . Prove that
R is a partial order relation.
Question 1. Equivalence Relation 1
Define a relation R on by iff .
Prove that R is an equivalence relation, that is, prove
that it is reflexive, symmetric, and transitive.
Determine the equivalence classes of this
relation.
What members are in the class [2]?
How many members do the equivalence classes have? Do
they all have the same number of members?
How many equivalence classes are there?
Question 2. Equivalence Relation 2
Consider the relation from last week defined
as:...
Suppose x,y ∈ R and assume that x < y. Show that for all z
∈ (x,y), there exists α ∈ (0,1) so that αx+(1−α)y = z. Now, also
prove that a set X ⊆ R is convex if and only if the set X satisfies
the property that for all x,y ∈ X, with x < y, for all z ∈
(x,y), z ∈ X.
Consider the following history H:
T2:R(Y), T1:R(X), T3:R(Y), T2:R(X), T2:W(Y), T2:Commit, T1:W(X),
T1:Commit, T3:R(X), T3:Commit
Assume that each transaction is consistent.
Does the final database state satisfy all integrity constraints?
Explain.
Let R be the relation on Z+× Z+ such that (a, b) R (c, d) if and
only if ad=bc. (a) Show that R is an equivalence relation. (b) What
is the equivalence class of (1,2)? List out at least five elements
of the equivalence class. (c) Give an interpretation of the
equivalence classes for R. [Here, an interpretation is a
description of the equivalence classes that is more meaningful than
a mere repetition of the definition of R. Hint:...