User leftaroundabout

83 votes

7 answers

11k views

Is linear algebra more “fully understood” than other maths disciplines?

asked Mar 16, 2016 at 21:03

43 votes

3 answers

11k views

Is it true that a space-filling curve cannot be injective everywhere?

asked Jun 3, 2011 at 22:28

12 votes

2 answers

547 views

Is it mathematically problematic to consider the complex space of real(!)-valued functions?

asked Apr 20, 2017 at 21:00

9 votes

2 answers

334 views

How should one interpret an interval like $[2,1]$?

asked Aug 14, 2011 at 21:29

9 votes

1 answer

381 views

What is the name for the archetypical example of a test function, $\varphi(x)=e^{1/(x^2-1)}$?

asked May 23, 2011 at 20:57

8 votes

1 answer

156 views

Is there a permutation on $\mathbb{N}$ that, if repeated often enough, eventually shuffles the whole set?

asked Aug 19, 2016 at 12:18

8 votes

3 answers

2k views

Is self-adjointness really a property of an operator, or of an operator and an inner product?

asked Jan 23, 2017 at 22:33

7 votes

3 answers

1k views

How is the uniform boundedness principle compatible with this seemingly weak convergent sequence?

asked May 19, 2011 at 10:36

6 votes

0 answers

84 views

Is there a way to define the concept of manifolds so it looks more like “generalised affine spaces”?

asked Jan 26, 2015 at 12:08

3 votes

1 answer

199 views

Why not define the Conway base-5 function, instead of base-13?

asked Feb 15, 2014 at 10:59

2 votes

1 answer

126 views

Are functions between sets of global elements of objects isomorphic to the hom-set between these objects?

asked Feb 6, 2014 at 13:29

2 votes

1 answer

92 views

Would it be appropriate to use "power" to describe an $n$-fold fold of a number with some associative binary operation? Is there a better expression?

asked Nov 3, 2011 at 18:45

2 votes

1 answer

103 views

What do you call a directed graph in which reachablility is a symmetric relation?

asked Jun 26, 2016 at 20:15

2 votes

2 answers

1k views

Why is the hyperbolic plane homeomorphic to $\mathbb{R}^2$, whilst the 2-sphere isn't?

asked Mar 30, 2018 at 15:19

2 votes

3 answers

94 views

Is there any shorter term for manifolds with boundary?

asked Sep 10, 2015 at 12:40

1 vote

1 answer

150 views

Can you say that almost all $\mathcal{C}^\infty$ functions are not polynomials?

asked Mar 29, 2015 at 12:50

0 votes

2 answers

3k views

How does the left singular value decomposition change when one duplicates a column in the original matrix?

asked Nov 25, 2012 at 17:53

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17 Questions

Is linear algebra more “fully understood” than other maths disciplines?

Is it true that a space-filling curve cannot be injective everywhere?

Is it mathematically problematic to consider the complex space of real(!)-valued functions?

How should one interpret an interval like $[2,1]$?

What is the name for the archetypical example of a test function, $\varphi(x)=e^{1/(x^2-1)}$?

Is there a permutation on $\mathbb{N}$ that, if repeated often enough, eventually shuffles the whole set?

Is self-adjointness really a property of an operator, or of an operator and an inner product?

How is the uniform boundedness principle compatible with this seemingly weak convergent sequence?

Is there a way to define the concept of manifolds so it looks more like “generalised affine spaces”?

Why not define the Conway base-5 function, instead of base-13?

Are functions between sets of global elements of objects isomorphic to the hom-set between these objects?

Would it be appropriate to use "power" to describe an $n$-fold fold of a number with some associative binary operation? Is there a better expression?

What do you call a directed graph in which reachablility is a symmetric relation?

Why is the hyperbolic plane homeomorphic to $\mathbb{R}^2$, whilst the 2-sphere isn't?

Is there any shorter term for manifolds with boundary?

Can you say that almost all $\mathcal{C}^\infty$ functions are not polynomials?

How does the left singular value decomposition change when one duplicates a column in the original matrix?