Limits of sequences - supremum and infimum, topology of R, Heine–Borel theorem, Bolzano–Weierstrass theorem, compactness equivalence to closed and bounded - One Line Questions

1. Which of the following is an example of a closed set in R? [0, 1]
2. Which of the following is an example of an open set in R? (0, 1)
3. Consider the set S = {1/n | n is a positive integer}. What is the supremum of S? 1
4. Consider the set S = {1/n | n is a positive integer}. What is the infimum of S? 0
5. If a sequence {a_n} is bounded, it does NOT necessarily have: A monotonic subsequence
6. If a subset of R is infinite and bounded, the Bolzano–Weierstrass theorem guarantees the existence of: A convergent subsequence
7. What is a limit point (or accumulation point) of a set S? A point such that every open interval containing it also contains a point of S different from the point itself.
8. What is the definition of a convergent sequence in real analysis? A sequence whose terms get arbitrarily close to a specific real number as the index increases.
9. In the topology of R, what is an open set? A set that is a union of open intervals.
10. A set S in R is closed if and only if it contains: All its limit points.
11. The Bolzano–Weierstrass theorem is a direct consequence of the: Completeness Property of R
12. Which property is equivalent to compactness for a subset of R? Being closed and bounded
13. Which theorem establishes an equivalence between compactness and being closed and bounded for subsets of R? Heine–Borel Theorem
14. Which property of real numbers is crucial for the existence of limits of sequences? Completeness property
15. The Bolzano–Weierstrass theorem is also known as the: Boundedness Theorem
16. The statement 'Every infinite bounded subset of R has a limit point' is the essence of which theorem? Bolzano–Weierstrass Theorem
17. Which of the following is a correct statement about the supremum (sup) and infimum (inf) of a non-empty set S of real numbers? If S is bounded above, sup S is the smallest real number that is greater than or equal to every element of S.
18. The Bolzano–Weierstrass theorem is crucial for proving that a continuous function on a compact set attains its: Maximum and minimum values
19. Consider the set of all rational numbers in the interval [0, 1]. This set is infinite and bounded. What does Bolzano–Weierstrass imply? It has a limit point within [0, 1].
20. What does it mean for a set to be compact in the context of real analysis? It must be bounded and contain all its limit points.
21. If a set K in R is compact, what can be said about any sequence {x_n} in K? It has a subsequence that converges to a point in K.
22. According to the Heine–Borel theorem, what is a necessary and sufficient condition for a subset of R to be compact? It must be closed and bounded.
23. If a sequence {a_n} converges to L, what can be said about its boundedness? It must be bounded.
24. The property that any sequence in a compact set K has a subsequence converging to a point in K is equivalent to: K being closed and bounded
25. If a sequence {a_n} converges to L, which of the following must be true? For every epsilon > 0, there exists N such that |a_n - L| < epsilon for all n >= N.
26. The Bolzano–Weierstrass theorem can be used to prove that every convergent sequence has a: Limit point
27. Consider the interval [0, 1]. Is it compact according to the Heine–Borel theorem? Yes, because it is closed and bounded.
28. If a set of real numbers is bounded above, does it necessarily have a supremum? Yes, by the completeness property of real numbers.
29. If a set S is closed and bounded, then S is: Compact
30. The Heine–Borel theorem implies that a closed and bounded interval [a, b] in R is: Compact
31. If a set K is compact in R, then K is necessarily: Bounded
32. If a set S is compact, it implies that S is: Sequentially compact
33. The Heine–Borel theorem states that a subset of R is compact if and only if it is: Closed and bounded
34. The definition of compactness using open covers is also known as: Heine–Borel Property
35. The Bolzano–Weierstrass theorem is a key result for proving the existence of: Limit points
36. If a sequence {a_n} has a limit L, then L is a: Limit point of the set {a_n | n in N}
37. What is a closed set in the topology of R? The complement of an open set.
38. What is the Heine–Borel theorem primarily concerned with? The property of compactness for subsets of R.
39. What does the topology of R refer to? The study of open sets, closed sets, and their properties on the real line.
40. Which of the following is NOT a property of closed sets in R? The intersection of any collection of closed sets is closed.
41. Let S be a non-empty set of real numbers bounded above. The supremum of S is: The smallest number that is greater than or equal to all elements of S.
42. Let S be a non-empty set of real numbers bounded below. The infimum of S is: The largest number that is less than or equal to all elements of S.
43. What is the supremum of a set of real numbers? The least upper bound of the set.
44. What is the infimum of a set of real numbers? The greatest lower bound of the set.
45. Which of the following is NOT a property of open sets in R? The union of any collection of open sets is open.
46. What is the relationship between the set of limit points of a set S and the closure of S? The set of limit points is a subset of the closure.
47. What is the relationship between the Bolzano–Weierstrass theorem and the Heine–Borel theorem? Heine–Borel is a consequence of Bolzano–Weierstrass and the definition of open sets.
48. What does the Bolzano–Weierstrass theorem state about bounded infinite subsets of R? They must have at least one limit point.
49. Consider the open interval (0, 1). Is it compact according to the Heine–Borel theorem? No, because it is not closed.
50. Consider the set of integers Z. Is it compact? No, it is not bounded.