Problem 1429 (difficulty: 3/10)

(a) What ring do the half-lines \(\displaystyle [a,\infty)\) generate?

(b) What \(\displaystyle \sigma\)-ring do the half-lines \(\displaystyle [a,\infty)\) generate?

(c) What is the smallest cardinality of a generating set of the \(\displaystyle \sigma\)-ring of Borel-sets?

Give me another random problem!