Which of the following statement(s) is(are) TRUE? a)There exists a con...
Statement A: There exists a connected set in R which is not compact
To prove this statement, we can consider the set of all real numbers, R. R is a connected set because it contains all the real numbers and there are no gaps or breaks in between. However, R is not compact because it is unbounded. We can always find an open cover for R that does not have a finite subcover. For example, we can consider the open cover consisting of the open intervals (-n, n) for all positive integers n. This cover covers the entire set R, but no finite number of intervals can cover R completely. Therefore, statement A is true.
Statement B: Arbitrary union of closed intervals in R need not be compact
To prove this statement, we can consider the union of closed intervals [n, n+1] for all positive integers n. Each individual closed interval [n, n+1] is compact because it is a closed and bounded set in R. However, the union of these intervals is not compact. We can construct an open cover for this union by considering open intervals (n-1, n+2) for all positive integers n. This cover covers the entire union, but no finite number of intervals can cover the union completely. Therefore, statement B is true.
Statement C: Arbitrary union of closed intervals in R is always closed
This statement is false. The arbitrary union of closed intervals in R may not always be closed. For example, consider the union of closed intervals [0, 1/n] for all positive integers n. Each individual closed interval [0, 1/n] is closed, but the union of these intervals is the half-open interval [0, 1) which is not closed. Therefore, statement C is false.
Statement D: Every bounded infinite subset R of R has a limit point in itself
This statement is true. By the Bolzano-Weierstrass theorem, every bounded sequence in R has a convergent subsequence. Therefore, every bounded infinite subset R of R has at least one limit point in itself. Therefore, statement D is true.
Which of the following statement(s) is(are) TRUE? a)There exists a con...
A