Question 8 Let R be relation on a set A. 1. When is R said to be an equivalence relation? Give a precise definition, using appropriate quantifiers etc. 2. When is R said to be an partial order? Give a precise definition, using appropriate quantifiers etc (You don't need to redefine things that you defined in the previous part... you may simply mention them to save time.) 3. On Z, define a relation: a D biff a - b is...
1. Recall the definition of red, green, blue numbers. Let R denote the set of red numbers. Let G be the set of green numbers, and let B denote the set of blue numbers. Is R S G S B = Z. Here Z is the set of all intergers. Explain.
#1 & 2 Exercise 2.121 Let R be a ring. Definition 2.121.1 The center of R, written Z(R), is defined to be the set {re R | rx = xr for all x € R}. 1. Show that Z(R) is a subring of R. 2. If R is commutative, what is Z(R)?
probelms 9.1 9 Modular arithmetic Definition 9.1 Let S be a set. A relation R = R(,y) on S is a statement about pairs (x,y) of elements of S. For r,y ES, I is related to y notation: Ry) if R(x,y) is true. A relation Ris: Reflexive if for any I ES, R. Symmetric if for any ry ES, Ry implies y Rr. Transitive if for any r.y.ES, Ry and yRimply R. An equivalence relation is a reflexive, symmetric and...
Let R={1 € Q[2] : [0) € Z}. (a) Show that R is an integral domain and R* = {+1}. (b) Show that irreducibles of Rare Ep for primes pe Z, and S() ER with (0 €{+1} which are irreducible in Q[r]. (c) Show that r is not a product of irreducibles, and hence R does not satisfy the ascending chain condition for principal ideals.
Q 1. Let S = {0, 1} × {a, b, a} × {0, 1, 2}. (a) Write out the set S in full, as a set of triples. Be careful to write your answer using correct set notation. (b) What is the cardinality of {a, b, a}? What is the cardinality of S?
Let U be the set of all integers. Consider the following sets: S is the set of all even integers; T is the set of integers obtained by tripling any one integer and adding 1; V is the set of integers that are multiples of 2 and 3. a) Use set builder notation to describe S, T and V symbolically. b) Compute s n T, s n V and T V. Describe these sets using set builder notation
16. (8 points) Let Z be the integers and let A - Zx Z. Define the relation R on A by (a, b) R(c, d) if and only if a c and b 3 d for all (a, b), (c, d)E A. Prove that R is a partial ordering on A that is not a total ordering. 16. (8 points) Let Z be the integers and let A - Zx Z. Define the relation R on A by (a, b)...
1) (a) Show that any set S in Q" is Z-linearly independent if and only if it is Q-linearly independent. (b) Let A be a non-trivial subgroup of Zn and φ : Zn → Zn Cz Q be the Z-module homomorphism given by a H> a&1. Using and Part (a), show that A is isomorphic to Zk where k . (a) Show that any set S in Q" is Z-linearly independent if and only if it is Q-linearly independent. (b)...
1. Let Q be the set of polynomials with rational coefficients. You may assume that this is an abelian group under addition. Consider the function Ql] Q[x] given by p(px)) = p'(x), where we are taking the derivative. Show that is a group homomorphism. Determine the kernel of 2. Let G and H be groups. Show that (G x H)/G is isomorphic to H. Hint: consider defining a surjective homomorphism p : Gx HH with kernel G. Then apply the...