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user119615
  • Member for 8 years, 7 months
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88 votes
8 answers
11k views

Does mathematics become circular at the bottom? What is at the bottom of mathematics? [duplicate]

22 votes
2 answers
24k views

the zeros of $\sin(z)$, where $z$ is a complex number

15 votes
1 answer
7k views

Markov chains: is "aperiodic + irreducible" equivalent to "regular"?

15 votes
6 answers
3k views

Why is one proof for Cauchy-Schwarz inequality easy, but directly it is hard?

15 votes
6 answers
2k views

When modelling a real world event by assuming it has probability p, what are we saying/assuming about how that event behaves?

14 votes
1 answer
2k views

Is this a way to construct mathematics?(logic vs. set theory)

13 votes
4 answers
1k views

mathematical proof vs. first-order logic deductions

13 votes
4 answers
1k views

Why isn't every element of the spectrum an eigenvalue? (Where is the error in my proof?)

12 votes
3 answers
997 views

Why is the collection of all algebraic extensions of F not a set?

12 votes
1 answer
806 views

Is there a connection between duality in linear programming and duality in functional analysis?

12 votes
3 answers
3k views

T compact if and only if $T^*T$ is compact.

12 votes
1 answer
1k views

Proving properties for the Poisson-process.

11 votes
0 answers
2k views

A random variable is symmetric if and only if its characteristic function is real-valued

10 votes
1 answer
2k views

The fundamental group of $\mathbb{R}^3$ with its non-negative half-axes removed

10 votes
1 answer
4k views

Why can the meromorphic function only have finitely many poles in the complex plane?

9 votes
5 answers
431 views

Is $\mathbb{Q}[\sqrt{2},\sqrt{3}]$ the same as $\mathbb{Q}(\sqrt{2},\sqrt{3})$?

9 votes
2 answers
3k views

Showing that the first hitting time of a closed set is a stopping time.

9 votes
4 answers
843 views

Could a version of probability theory be made rigorous with only calculus?

8 votes
1 answer
2k views

Theta-space is a deformation retraction of the doubly-punctured plane, how to find equations.

7 votes
1 answer
2k views

All projections are continuous in a Banach space.

7 votes
1 answer
15k views

Can we change order of integration and differentiation here.

7 votes
1 answer
339 views

How to show that the group is abelian?

7 votes
2 answers
3k views

Can it be proved that a Meromorphic function only has a countable number of poles?

7 votes
1 answer
1k views

Are Borel-measurable functions limits of sequences of continuous functions

7 votes
2 answers
6k views

Sigma-algebra requirement 3, closed under countable unions.

7 votes
2 answers
1k views

Big-oh notation for complex functions.

7 votes
2 answers
2k views

Good book that contains stochastic integration, martingales and Lévy-processes?

6 votes
2 answers
343 views

Showing that this is a martingale.(4.13 in Øksendals SDE)

6 votes
1 answer
869 views

When is the compensated Poisson random measure a martingale ? (extensions to sets not bounded from 0)

6 votes
2 answers
746 views

The jumping times of a càdlàg process are stopping times.

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