Assignment:
Let X= R ( real numbers): consider the set of all half lines open to the left U= {(a, infinity) : a element R} and the set A = U Union { empty set, R}. is set A a sigma algebra?
What if we replace set U with the set V = {(a, infinity), (- infinity, b) : a,b are elements of R} of all half lines on R? is A a sigma algebra?
Provide complete and step by step solution for the question and show calculations and use formulas.