User SK19

22 votes

Is mathematics just a bunch of nested empty sets?

answered May 2, 2018 at 16:40

13 votes

Accepted

Getting to know the Mizar Mathematical Library

answered Jun 3, 2018 at 13:54

9 votes

Is the product of all positive rational numbers equal to one?

answered Feb 18, 2018 at 17:23

8 votes

Is there any result that has applications that can't be proved in constructive mathematics?

answered May 6, 2018 at 10:51

7 votes

What is the difference between Formal Logic and Proofs?

answered Sep 26, 2019 at 6:34

6 votes

In the surreal numbers, is it fair to say $0.9$ repeating is not equal to $1$?

answered Mar 6, 2018 at 23:03

4 votes

Is maths inductive or deductive?

answered Dec 2, 2017 at 15:16

4 votes

Accepted

Surreal arithmetic with $\frac{1}{2}\omega$

answered Dec 8, 2017 at 18:50

4 votes

Accepted

I know $\mathbb{R}$ is the real number line. What really is $\mathbb{R}^n$?

answered Mar 7, 2018 at 0:36

4 votes

Accepted

Probability questions involving complements

answered May 10, 2018 at 18:47

4 votes

If $x$ is irrational, can $-x^3+x^2+x$ be rational?

answered Jan 31 at 17:51

3 votes

Accepted

3-edge colorability of planar, triangle-free graphs of maximum degree 3

answered Mar 19, 2019 at 21:44

3 votes

Accepted

Absolute value of a determinant

answered May 9, 2018 at 15:52

3 votes

$\frac{1}{\infty-\infty}$ is an indeterminate form?

answered Dec 3, 2017 at 0:10

2 votes

Accepted

well ordered set on dictionary order

answered Dec 8, 2017 at 21:23

2 votes

Why does the inverse of surreal numbers exist?

answered Dec 7, 2017 at 9:47

2 votes

Accepted

Proof for $f(x)=e^x+x$ strictly increasing

answered Feb 23, 2018 at 4:39

2 votes

Accepted

Convergence on variants of the Harmonic series

answered Feb 19, 2018 at 13:16

2 votes

Accepted

Counter argument for the characterization of intervals.

answered Feb 18, 2018 at 18:01

2 votes

Accepted

Infinite unions, sets, inclusion

answered Feb 20, 2018 at 19:43

2 votes

Accepted

Power set of an identity is equal to the identity of power set?

answered May 8, 2018 at 23:54

2 votes

Accepted

Define powerset P(f) (P(real numbers)

answered May 9, 2018 at 1:05

2 votes

Accepted

Suppose $\phi : G \rightarrow H$ is an isomorphism, and $g\in G$. Prove that $\text{ord}(\phi(g))= \text{ord}(g)$.

answered May 10, 2018 at 15:17

2 votes

Accepted

Graph Theory (Edge connectivity of a complete bipartite graph $K_{m,n}$

answered Mar 17, 2020 at 0:59

2 votes

In TG, what is the purpose of the "set axiom"

answered May 13, 2018 at 6:33

2 votes

Worrying about logic and foundations too much

answered May 6, 2018 at 17:12

2 votes

Accepted

Learning about subsets

answered Oct 17, 2019 at 21:49

2 votes

How to build a graph with these properties?

answered Mar 16, 2020 at 15:51

2 votes

Neatly draw two graphs with at least five vertices with the same degree sequence, where one is a tree and the other is not a tree.

answered May 9, 2019 at 20:40

2 votes

Accepted

How to prove that 2 sets are equinumerous?

answered Mar 20, 2020 at 20:59

Stack Exchange Network

102 Answers

Is mathematics just a bunch of nested empty sets?

Getting to know the Mizar Mathematical Library

Is the product of all positive rational numbers equal to one?

Is there any result that has applications that can't be proved in constructive mathematics?

What is the difference between Formal Logic and Proofs?

In the surreal numbers, is it fair to say $0.9$ repeating is not equal to $1$?

Is maths inductive or deductive?

Surreal arithmetic with $\frac{1}{2}\omega$

I know $\mathbb{R}$ is the real number line. What really is $\mathbb{R}^n$?

Probability questions involving complements

If $x$ is irrational, can $-x^3+x^2+x$ be rational?

3-edge colorability of planar, triangle-free graphs of maximum degree 3

Absolute value of a determinant

$\frac{1}{\infty-\infty}$ is an indeterminate form?

well ordered set on dictionary order

Why does the inverse of surreal numbers exist?

Proof for $f(x)=e^x+x$ strictly increasing

Convergence on variants of the Harmonic series

Counter argument for the characterization of intervals.

Infinite unions, sets, inclusion

Power set of an identity is equal to the identity of power set?

Define powerset P(f) (P(real numbers)

Suppose $\phi : G \rightarrow H$ is an isomorphism, and $g\in G$. Prove that $\text{ord}(\phi(g))= \text{ord}(g)$.

Graph Theory (Edge connectivity of a complete bipartite graph $K_{m,n}$

In TG, what is the purpose of the "set axiom"

Worrying about logic and foundations too much

Learning about subsets

How to build a graph with these properties?

Neatly draw two graphs with at least five vertices with the same degree sequence, where one is a tree and the other is not a tree.

How to prove that 2 sets are equinumerous?