User NNOX Apps

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NNOX Apps

Member for 9 years, 7 months
Last seen more than a month ago

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152 Answers

Score Activity Newest

28 votes

How can I prove $\sup(A+B)=\sup A+\sup B$ if $A+B=\{a+b\mid a\in A, b\in B\}$

answered Mar 3, 2014 at 14:44

17 votes

Math and mental fatigue

soft-question advice learning

answered Apr 5, 2014 at 17:03

16 votes

How to define a bijection between $(0,1)$ and $(0,1]$?

functions elementary-set-theory

answered Nov 6, 2013 at 6:51

13 votes

Union of two vector subspaces not a subspace?

linear-algebra

answered Oct 26, 2013 at 14:10

7 votes

Cardinality of the set of all real functions of real variable

elementary-set-theory cardinals

answered Nov 7, 2013 at 9:49

6 votes

Is there any difference between mapping and function?

soft-question terminology

answered Jan 29, 2014 at 6:49

5 votes

How can I prove $\sup(A+B)=\sup A+\sup B$ if $A+B=\{a+b\mid a\in A, b\in B\}$

real-analysis supremum-and-infimum sumset

answered Mar 3, 2014 at 16:22

5 votes

What is the integral of 0?

calculus integration proof-writing

answered Apr 29, 2014 at 14:43

5 votes

More examples of Simpson's Paradox, barring the ones on Wikipedia, Titanic, and delayed flights.

statistics examples-counterexamples

answered Dec 25, 2017 at 17:34

5 votes

Abductive vs. inductive reasoning

logic philosophy

answered Feb 3, 2017 at 5:50

5 votes

Understanding the P-value

statistics hypothesis-testing

answered Apr 19, 2019 at 20:48

4 votes

Is a bijective map between two groups always an isomorphism?

abstract-algebra group-theory group-isomorphism

answered Feb 5, 2014 at 8:16

4 votes

Why does L'Hôpital's rule work?

calculus

answered Mar 7, 2014 at 7:52

4 votes

Do the real numbers and the complex numbers have the same cardinality?

complex-numbers cardinals

answered Nov 6, 2013 at 13:18

4 votes

Accepted

Why is the universal quantifier $\forall x \in A : P(x)$ defined as $\forall x (x \in A \implies P(x))$ using an implication?

logic definition quantifiers

answered Aug 27, 2013 at 8:56

4 votes

Image of subgroup and Kernel of homomorphism form subgroups

group-theory

answered Jan 8, 2014 at 13:41

4 votes

Which do you recommend for learning how to write proofs — How to Prove it by Velleman, or How to Solve it by Polya?

reference-request proof-writing book-recommendation

answered Jul 20, 2013 at 14:27

3 votes

Which do you recommend for learning how to write proofs — How to Prove it by Velleman, or How to Solve it by Polya?

reference-request proof-writing book-recommendation

answered Jul 20, 2013 at 15:22

3 votes

$H$ is a maximal normal subgroup of $G$ if and only if $G/H$ is simple.

group-theory

answered Feb 8, 2014 at 15:54

3 votes

Prove $\sup(f+g) \le \sup f + \sup g$

real-analysis

answered Mar 7, 2014 at 13:59

3 votes

Is "integrability" equivalent to "having antiderivative"?

real-analysis integration

answered Mar 9, 2014 at 15:37

3 votes

If $A^2+2A+I_n=O_n$ then $A$ is invertible

linear-algebra matrices

answered Jul 27, 2020 at 20:06

3 votes

Why is negative times negative = positive?

abstract-algebra algebra-precalculus arithmetic education faq

answered Jan 7, 2019 at 21:51

3 votes

What is a good way to think of Factor Groups?

abstract-algebra group-theory finite-groups

answered Feb 19, 2014 at 18:47

3 votes

What is the difference between an indefinite integral and an antiderivative?

calculus terminology

answered Mar 13, 2014 at 12:35

3 votes

Typo in Spivak's explanation of limits in Calculus?

calculus limits inequality

answered May 26, 2018 at 6:42

2 votes

Intuitively, why does Bayes' theorem work?

probability intuition bayes-theorem

answered Jan 22, 2019 at 1:25

2 votes

Bounded sequence and every convergent subsequence converges to L

real-analysis convergence-divergence

answered May 1, 2014 at 11:39

2 votes

What is the difference between an indefinite integral and an antiderivative?

calculus terminology

answered Mar 9, 2014 at 15:08

2 votes

More examples of Simpson's Paradox, barring the ones on Wikipedia, Titanic, and delayed flights.

statistics examples-counterexamples

answered May 3, 2019 at 7:42

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152 Answers

How can I prove $\sup(A+B)=\sup A+\sup B$ if $A+B=\{a+b\mid a\in A, b\in B\}$

Math and mental fatigue

How to define a bijection between $(0,1)$ and $(0,1]$?

Union of two vector subspaces not a subspace?

Cardinality of the set of all real functions of real variable

Is there any difference between mapping and function?

How can I prove $\sup(A+B)=\sup A+\sup B$ if $A+B=\{a+b\mid a\in A, b\in B\}$

What is the integral of 0?

More examples of Simpson's Paradox, barring the ones on Wikipedia, Titanic, and delayed flights.

Abductive vs. inductive reasoning

Understanding the P-value

Is a bijective map between two groups always an isomorphism?

Why does L'Hôpital's rule work?

Do the real numbers and the complex numbers have the same cardinality?

Why is the universal quantifier $\forall x \in A : P(x)$ defined as $\forall x (x \in A \implies P(x))$ using an implication?

Image of subgroup and Kernel of homomorphism form subgroups

Which do you recommend for learning how to write proofs — How to Prove it by Velleman, or How to Solve it by Polya?

Which do you recommend for learning how to write proofs — How to Prove it by Velleman, or How to Solve it by Polya?

$H$ is a maximal normal subgroup of $G$ if and only if $G/H$ is simple.

Prove $\sup(f+g) \le \sup f + \sup g$

Is "integrability" equivalent to "having antiderivative"?

If $A^2+2A+I_n=O_n$ then $A$ is invertible

Why is negative times negative = positive?

What is a good way to think of Factor Groups?

What is the difference between an indefinite integral and an antiderivative?

Typo in Spivak's explanation of limits in Calculus?

Intuitively, why does Bayes' theorem work?

Bounded sequence and every convergent subsequence converges to L

What is the difference between an indefinite integral and an antiderivative?

More examples of Simpson's Paradox, barring the ones on Wikipedia, Titanic, and delayed flights.