For sets A and B, define A+B = {a + b: a € A, b E B}. (a) Prove that if A and B are open, then A+ B is open. (b) Prove that if A and B are compact, then A+ B is compact. (c) It is not true that the sum of closed sets must be closed. Provide an example to demonstrate this.
For sets A and B, define A+B = {a + b: a € A, b E B}. (a) Prove that if A and B are open, then A+ B is open. (b) Prove that if A and B are compact, then A+ B is compact. (c) It is not true that the sum of closed sets must be closed. Provide an example to demonstrate this.
Elements Of Modern Algebra
8th Edition
ISBN:9781285463230
Author:Gilbert, Linda, Jimmie
Publisher:Gilbert, Linda, Jimmie
Chapter2: The Integers
Section2.4: Prime Factors And Greatest Common Divisor
Problem 17E
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Can you please answer all three parts simply, or just the last two (b,c). Either way, Im just looking for a simple soultion for a better understanding. Thank you.
![For sets A and B, define A+ B = {a +b: a € A, b e B}.
(a) Prove that if A and B are open, then A+ B is open.
(b) Prove that if A and B are compact, then A+ B is compact.
(c) It is not true that the sum of closed sets must be closed. Provide an example to demonstrate
this.](/v2/_next/image?url=https%3A%2F%2Fcontent.bartleby.com%2Fqna-images%2Fquestion%2Fbcac37ab-99fb-4492-b15f-6751da0b26b9%2F9810fd12-d059-433e-aad2-d2ecf2480663%2Fncsydes_processed.png&w=3840&q=75)
Transcribed Image Text:For sets A and B, define A+ B = {a +b: a € A, b e B}.
(a) Prove that if A and B are open, then A+ B is open.
(b) Prove that if A and B are compact, then A+ B is compact.
(c) It is not true that the sum of closed sets must be closed. Provide an example to demonstrate
this.
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