Metric Spaces and Topology
This quiz covers fundamental concepts and theorems related to metric spaces and topology.
Questions
Which of the following is NOT a metric space?
- (R, d(x, y) = |x - y|)
- (Q, d(x, y) = |x - y|)
- (C, d(x, y) = |x - y|)
In a metric space (X, d), a set E is open if:
- For each x in E, there exists an r > 0 such that B_r(x) ⊆ E
- For each x in E, there exists an r > 0 such that B_r(x) ∩ E = ∅
- For each x in E, there exists an r > 0 such that B_r(x) ⊆ X - E
In a metric space (X, d), a set E is closed if:
- For each x in E, there exists an r > 0 such that B_r(x) ⊆ E
- For each x in E, there exists an r > 0 such that B_r(x) ∩ E = ∅
- For each x in X - E, there exists an r > 0 such that B_r(x) ∩ E = ∅
Which of the following functions is continuous on the real line R?
- f(x) = 1/x
- f(x) = |x|
- f(x) = sin(x)
In a topological space (X, τ), a subset E is compact if:
- Every open cover of E has a finite subcover
- Every sequence in E has a convergent subsequence
- Every continuous function from E to R is bounded
Which of the following is a topological property?
- Boundedness
- Continuity
- Compactness
In a metric space (X, d), a sequence (x_n) is Cauchy if:
- For every ε > 0, there exists an N such that d(x_n, x_m) < ε for all n, m > N
- For every ε > 0, there exists an N such that d(x_n, x_N) < ε for all n > N
- For every ε > 0, there exists an N such that d(x_N, x_M) < ε for all N, M > n
Which of the following is a complete metric space?
- (R, d(x, y) = |x - y|)
- (Q, d(x, y) = |x - y|)
- (C, d(x, y) = |x - y|)
In a topological space (X, τ), a subset E is dense if:
- Every non-empty open set in X intersects E
- Every point in X is contained in E
- Every closed set in X contains E
Which of the following is a Hausdorff space?
- (R, d(x, y) = |x - y|)
- (Q, d(x, y) = |x - y|)
- (C, d(x, y) = |x - y|)
In a metric space (X, d), a function f: X → Y is continuous at a point x_0 if:
- For every ε > 0, there exists a δ > 0 such that d(x, x_0) < δ implies d(f(x), f(x_0)) < ε
- For every ε > 0, there exists a δ > 0 such that d(x, x_0) < ε implies d(f(x), f(x_0)) < δ
- For every ε > 0, there exists a δ > 0 such that d(f(x), f(x_0)) < δ implies d(x, x_0) < ε
Which of the following is a connected space?
- (R, d(x, y) = |x - y|)
- (Q, d(x, y) = |x - y|)
- (C, d(x, y) = |x - y|)
In a topological space (X, τ), a subset E is nowhere dense if:
- The interior of E is empty
- The closure of E is empty
- The boundary of E is empty
Which of the following is a locally compact space?
- (R, d(x, y) = |x - y|)
- (Q, d(x, y) = |x - y|)
- (C, d(x, y) = |x - y|)
In a metric space (X, d), a sequence (x_n) converges to a point x if:
- For every ε > 0, there exists an N such that d(x_n, x) < ε for all n > N
- For every ε > 0, there exists an N such that d(x_n, x) > ε for all n > N
- For every ε > 0, there exists an N such that d(x_n, x) = ε for all n > N