Prove or disprove the following statements.
(a) There is a simple graph with 6 vertices with degree sequence
(3, 3, 5, 5, 5, 5)?
(b) There is a simple graph with 6 vertices with degree sequence
(2, 3, 3, 4, 5, 5)?
Prove or disprove each of the following statements.
(a) There exists a prime number x such that x + 16 and x + 32
are also prime numbers.
(b) ∀a, b, c, m ∈ Z +, if a ≡ b (mod m), then c a ≡ c b (mod
m).
(c) For any positive odd integer n, 3|n or n 2 ≡ 1 (mod 12).
(d) There exist 100 consecutive composite integers.
Prove or disprove the statements: (a) If x is a real number such
that |x + 2| + |x| ≤ 1, then x 2 + 2x − 1 ≤ 2.
(b) If x is a real number such that |x + 2| + |x| ≤ 2, then x 2
+ 2x − 1 ≤ 2.
(c) If x is a real number such that |x + 2| + |x| ≤ 3, then x 2
+ 2x − 1 ≤ 2....
(1) For each of the following statements, write its negation.
Then prove or disprove the original statement.
(b) ∃x ∈ R, ∀y ∈ R, ∃z ∈ R, x2 + y2 +
z2 ≥ 1.
(c) ∀y ∈ N, ∃x ∈ N, y = 2x + 1.
(d) x ∈ R ⇒ x2 ≥ 0.
(e) x ∈ [0, 1] ⇒ x > 2x − 1.
(f) For all real numbers x and y, x > y ⇔ x2 >
y2
Let U = {(x1,x2,x3,x4) ∈F4 | 2x1 = x3, x1 + x4 = 0}.
(a) Prove that U is a subspace of F4.
(b) Find a basis for U and prove that dimU = 2.
(c) Complete the basis for U in (b) to a basis of F4.
(d) Find an explicit isomorphism T : U →F2.
(e) Let T as in part (d). Find a linear map S: F4 →F2 such that
S(u) = T(u) for all u ∈...
Prove E(X1 + X2 | Y=y) = E(X1 |
Y=y) + E(X2 |Y=y). Prove both cases where all random
variables are discrete and also when all random variables are
continuous.