Cameron Buie's user avatar
Cameron Buie's user avatar
Cameron Buie's user avatar
Cameron Buie
  • Member for 12 years
  • Last seen this week
  • Missouri, United States
88 votes
Accepted

Show that the set of all finite subsets of $\mathbb{N}$ is countable.

55 votes

Is there a bijective map from $(0,1)$ to $\mathbb{R}$?

55 votes
Accepted

Why is $\sqrt{8}/2$ equal to $\sqrt{2}$?

44 votes
Accepted

How is an empty set truly "empty"?

42 votes
Accepted

Is the set of all valid C++ programs countably infinite?

41 votes
Accepted

In Group theory proofs what is meant by "well defined"

38 votes

How is $xy=1$ closed in $\Bbb{R}^2$?

34 votes

If a lottery has 300 tickets, shouldn't I win every 300 times I play

34 votes
Accepted

Are There Any Symbols for Contradictions?

33 votes

Solve $\cos^2x-\sin^2x= 1$

32 votes
Accepted

The inverse of a lower triangular matrix is lower triangular

31 votes
Accepted

Set of Linear equation has no solution or unique solution or infinite solution?

30 votes
Accepted

Dimension of the sum of two vector subspaces

29 votes

Is the null set a subset of every set?

29 votes

What's between the finite and the infinite?

29 votes
Accepted

How many positive integers $< 1{,}000{,}000$ contain the digit $2$?

28 votes
Accepted

Is every open subset of $ \mathbb{R} $ uncountable?

24 votes
Accepted

Computing the indefinite integral $\int x^n \sin x\,dx$

22 votes
Accepted

Induction: $\sum_{k=0}^n \binom nk k^2 = n(1+n)2^{n-2}$

22 votes
Accepted

Singularity at infinity of a function entire

21 votes
Accepted

example of a set that is closed and bounded but not compact

21 votes
Accepted

Contraction Map on Compact Normed Space has a Fixed Point

20 votes
Accepted

Can a function with just one point in its domain be continuous?

20 votes
Accepted

Proof of convexity of $f(x)=x^2$

19 votes

Prove: If a sequence converges, then every subsequence converges to the same limit.

19 votes

Your favourite application of the Baire Category Theorem

18 votes
Accepted

Examples of non-measurable sets in $\mathbb{R}$

18 votes

Prove a square is homeomorphic to a circle

18 votes

Find $x$ and $y$ in $2^{x-y} + 1 = 2^x,$ where $x,y$ are integers

17 votes

A "non-trivial" example of a Cauchy sequence that does not converge?

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