jlammy's user avatar
jlammy's user avatar
jlammy's user avatar
jlammy
  • Member for 8 years, 2 months
  • Last seen more than a week ago
  • London, United Kingdom
44 votes

Striking applications of linearity of expectation

20 votes
Accepted

$e^{-nx}\cdot\sum_{k=0}^\infty\frac{(nx)^k}{k!}f\left(\frac{k}{n}\right)\to f(x)$ for $f$ continuous and bounded

19 votes
Accepted

Solve $ab(a^2+b^2)=2c^4$ over $\mathbb Z$

14 votes
Accepted

Prove that inequality $AM \cdot AN + BM \cdot BN + CM \cdot CN \geq DM \cdot DN$

9 votes
Accepted

Permutations of race positions

8 votes
Accepted

How can I prove that $\frac{a}{2} + \frac{x}{a} \geq \sqrt{2x}$

8 votes
Accepted

$M^n-I$ invertible implies $M$ nilpotent over finite field

8 votes
Accepted

USA MO 1980's inequality

7 votes
Accepted

Martingale and linear function

7 votes
Accepted

Condition for probability of even number heads to be $1/2$

7 votes
Accepted

2 dimensional symmetric random walk

7 votes

Pairwise independence implies X+Y is independent from Z

7 votes
Accepted

Expected length of orbit for random permutation

6 votes
Accepted

British Maths Olympiad Round 2 2011, Question 3: Is there a more efficient method?

6 votes
Accepted

Hitting time of simple random walk

6 votes
Accepted

Dart expected number of throws problem

6 votes
Accepted

Differentiation of inner product with matrices

6 votes
Accepted

$\mathbb E[ |X| ] < \infty \iff \forall \epsilon : \mathbb E[ |X / \epsilon | ] < \infty$

5 votes
Accepted

Show $Q(x)\cdot Q(y)=x\cdot y\Rightarrow Q^TQ=I$

5 votes
Accepted

Convergence a.s of the sequence $\frac{X_n}{S_n}$

5 votes
Accepted

Show that the Matrix mapping f defined as $f(A) = A^p$ is differentiable

5 votes

How would one solve $z^6+z^4+z^3+z^2+1=0$?

5 votes
Accepted

Resolve $x+\frac{1}{x}$

5 votes

Four dice are tossed let $N$ be the number of distinct outcomes. Find $E[N]$

5 votes
Accepted

Given 3 events, $S_1$, $S_2$, $S_3$, how do I express $((S_1 \cup S_2) \cap (S_2 \cup S_3) \cap (S_3 \cup S_1))$ more concisely?

5 votes
Accepted

Given a triangle $ABC$ and its incenter I. If $P,Q$ are points on BI and CI so that $2PAQ=BAC$. Prove that $PDQ=90$

5 votes

Derivative of matrix inverse using definition of Frechet derivative

5 votes
Accepted

How do I calculate an integral like $\oint \vec{E}^{\,} \cdot \vec{dA}^{\,}$?

4 votes

Evaluating $\lim _{z \rightarrow \infty} z e^{-\frac{1}{2} z^{2}}$ using L'Hospital's Rule

4 votes
Accepted

$i+j-1$ tokens on row $i$ column $j$ of square grid

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