0
Still curious? Ask our experts.
Chat with our AI personalities
Ross
Taiga
BlakeAdd your answer:
Earn +20 pts
Are the real numbers a borel set?
Yes, since the set of real numbers can be expressed as a countable union of closed sets.In fact if we're talking about subsets of the real numbers (R), then by definition R is in all sigma-algebras of R including the Borel sigma-algebra, and so is a Borel set.
Give an example of a subset of R that is not a Borel set?
An example is given here: http://en.wikipedia.org/wiki/Non-Borel_set Any set that is easy to think of will be a Borel set, so an example of a non-Borel set will be complicated. Another approach: All Borel sets are Lebesgue measurable. The axiom of choice can be used to give an example of a non-measurable set, and this set will also be a non-Borel set. See http://en.wikipedia.org/wiki/Non-measurable_set = =
What is example of subset in math?
The set of Rational Numbers is a [proper] subset of Real Numbers.
Why singleton set is not open in Q?
In the context of the rational numbers ( \mathbb{Q} ) with the standard topology induced by the real numbers ( \mathbb{R} ), a singleton set ( {q} ) (where ( q ) is a rational number) is not open because for any point ( q ) in ( \mathbb{Q} ), every open interval around ( q ) contains both rational and irrational numbers. Therefore, any interval ( (q - \epsilon, q + \epsilon) ) intersects with points outside the singleton set, meaning it cannot be entirely contained within ( {q} ). Thus, singleton sets do not satisfy the definition of an open set in ( \mathbb{Q} ).
What a equal sets?
What are equal sets?? A set is a grouping of numbers. Set P = {1,4,9} if set Q is equal it must contain exactly the same numbers.
