No. The basic idea of proving why not is this:
1) The underlying space X is at least countably infinite (of course).
2) Use the properties of a sigma field (aka sigma algebra) to find a countable partition of the space, X = disjiont-union( X_i ).
3) Notice that the union(X_i, s in S) is in the sigma algebra for any subset S of natural numbers.
4) Notice that any union(X_i, s in S) is distinct.
5) Conclude, since the set of subsets of natural numbers is uncountable, so too is your sigma algebra.
No, it is countably infinite.
There are finite sets, countably infinite sets and uncountably infinite sets.
Closed sets and open sets, or finite and infinite sets.
An infinite set whose elements can be put into a one-to-one correspondence with the set of integers is said to be countably infinite; otherwise, it is called uncountably infinite.
No, it is not.
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The number of elements of a pid may be finite or countably infinite...or infinite also....but a finite field is always a pid
No, it is countably infinite.
There are finite sets, countably infinite sets and uncountably infinite sets.
No. The set of irrational numbers has the same cardinality as the set of real numbers, and so is uncountable.The set of rational numbers is countably infinite.
Yes, there are countably infinite rationals but uncountably infinite irrationals.
One possible classification is finite, countably infinite and uncountably infinite.
Countably infinite means you can set up a one-to-one correspondence between the set in question and the set of natural numbers. It can be shown that no such relationship can be established between the set of real numbers and the natural numbers, thus the set of real numbers is not "countable", but it is infinite.
Closed sets and open sets, or finite and infinite sets.
Yes, because it is countably infinite.
An infinite set whose elements can be put into a one-to-one correspondence with the set of integers is said to be countably infinite; otherwise, it is called uncountably infinite.
Easily. Indeed, it might be empty. Consider the set of positive odd numbers, and the set of positive even numbers. Both are countably infinite, but their intersection is the empty set. For a non-empty intersection, consider the set of positive odd numbers, and 2, and the set of positive even numbers. Both are still countably infinite, but their intersection is {2}.