Mark Joshi's user avatar
Mark Joshi's user avatar
Mark Joshi's user avatar
Mark Joshi
  • Member for 10 years, 4 months
  • Last seen more than 6 years ago
38 votes

The logarithm is non-linear! Or isn't it?

13 votes
Accepted

Prove that a subspace of dimension $n$ of a vector space of dimension $n$ is the whole space.

11 votes
Accepted

Show that function with compact support are integrable.

10 votes

Why are eigenvalues of nilpotent matrices equal to zero?

8 votes

What are some results that shook the foundations of one or more fields of mathematics?

8 votes
Accepted

How small is Diff(M) compared to Homeo(M)?

8 votes

Points in the unit disk

8 votes

If $4=5$, then $6=8\,$ (yes or no?)

7 votes

is every totally geodesic submanifold the set of fixed points of some isometries?

7 votes

Proving openness of a set in $\Bbb R^4$

7 votes

If $f(f(x)) = x $ has at most 1 solution, then so does $f(x) = x$.

7 votes
Accepted

What is the radius of convergence of $\displaystyle\sum_{n=0}^{\infty}z^{n^2}$

6 votes

Is it technically incorrect to write proofs forward?

6 votes

What is meant by a stopping time?

5 votes

Show that no non-trivial open set in $\mathbb{R}^n$ has measure zero in $\mathbb{R}^n$

5 votes

If $\nabla f(x) = 0$ on a set $S$, is $f$ necessarily constant on $S$?

5 votes

Showing that a function is strictly increasing

5 votes

Prove that $x+\sin x$ is strictly increasing

5 votes

Prove that $f$ is identically zero.

5 votes
Accepted

Prove $\mathbb{Q} \cap [0, 1] \subseteq \mathbb{R}$ is not compact

5 votes
Accepted

Proof that the exponential martingale is a Brownian Motion

5 votes

Why is radian so common in maths?

4 votes

smallest sigma algebra

4 votes

Is $\forall r \in \mathbb{R}, r^3 \notin \mathbb{Q} \implies r \notin \mathbb{Q}$ true?

4 votes

Settle a classroom argument - do there exist any functions that satisfy this property involving Taylor polynomials?

4 votes

Find $\lim_{x \to \infty} \left(\frac{x^2+1}{x^2-1}\right)^{x^2}$

4 votes

The closed unit ball is not compact in infinite dimension spaces. Why?

4 votes
Accepted

The differentiability of $f$ implies that $f'$ is continuous

4 votes

The cantor set is uncountable

4 votes
Accepted

How many dice would I need to get an $n$ of a kind 100% of the time?

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