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Demosthene's user avatar
Demosthene
  • Member for 9 years, 7 months
  • Last seen more than a week ago
46 votes
6 answers
168k views

Proof for the curl of a curl of a vector field

10 votes
2 answers
6k views

Proving the Ricci identity

5 votes
1 answer
129 views

On average, where is the lift?

5 votes
4 answers
2k views

Asymptotic behaviour / non-linear ODE

4 votes
1 answer
414 views

Building matrices from eigenvalues

4 votes
2 answers
801 views

Functional completeness for a ternary operator

4 votes
3 answers
2k views

$U(n)$ is a subgroup of $SO(2n)$

4 votes
1 answer
128 views

Lie bracket of $\mathfrak{so}(3)$

3 votes
5 answers
9k views

How to measure the radius of a sphere?

3 votes
1 answer
188 views

Argue that if a sentence has a proof, then it is a tautology

3 votes
1 answer
1k views

Every complete axiomatizable theory is decidable

2 votes
2 answers
696 views

Properties of the deductive closure

2 votes
1 answer
1k views

"Well-defined" ordering on the set of equivalence classes

2 votes
1 answer
183 views

Proof for a statement on prime numbers

2 votes
1 answer
919 views

First-Order Logic: semantic entailment and disjunction

2 votes
1 answer
191 views

Representable functions - Enderton

1 vote
1 answer
540 views

Consistent recursively axiomatizable theory

1 vote
1 answer
999 views

Rule T in First-Order Logic

1 vote
1 answer
240 views

Prove $\vdash\forall x(\alpha\to\beta)\to(\exists x\alpha\to\exists x\beta)$

1 vote
1 answer
249 views

Intuition about antisymmetrizing tensor equations

1 vote
0 answers
191 views

Decomposition of semi-simple Lie algebras

0 votes
2 answers
577 views

Logic : unsatisfiable set

0 votes
1 answer
57 views

Help solving non-trivial logarithmic inequality