User Jeff Strom

115 votes

Nontrivial theorems with trivial proofs

answered Jun 20, 2010 at 14:24

99 votes

Why do we teach calculus students the derivative as a limit?

answered Sep 27, 2010 at 13:58

69 votes

Can a subset of the plane have nontrivial $H_2$ or $\pi_2$?

answered Dec 9, 2014 at 21:32

58 votes

Can a mathematical definition be wrong?

answered Aug 6, 2010 at 23:36

40 votes

What are some noteworthy "mic-drop" moments in math?

answered Mar 11, 2019 at 0:22

40 votes

In a topological space if there exists a loop that cannot be contracted to a point does there exist a simple loop that cannot be contracted also?

answered Aug 9, 2019 at 1:23

33 votes

Accepted

Is every real n-manifold isomorphic to a quotient of $\mathbb{R}^n$?

answered Nov 13, 2010 at 21:50

32 votes

Accepted

Suspension of a topological space

answered Jun 3, 2021 at 0:57

31 votes

Main statement as theorem or corollary

answered Jan 15, 2018 at 14:09

30 votes

The role of the mean value theorem (MVT) in first-year calculus

answered Jul 11, 2010 at 23:05

27 votes

Accepted

Interesting Calculus Questions/Exercises

answered Jan 21, 2011 at 21:10

27 votes

Why is it so hard to compute $\pi_n(S^n)$?

answered Oct 21, 2014 at 17:46

25 votes

Accepted

Image of a map on cohomology rings

answered Sep 25, 2019 at 0:01

24 votes

Accepted

Homotopy equivalent Postnikov sections but not homotopy equivalent

answered Jul 30, 2020 at 17:14

21 votes

Accepted

Whitehead theorem for cohomotopy

answered May 13, 2014 at 0:49

20 votes

Advantages of working with CW complexes/spaces over Kan complexes/simplicial sets?

answered Jul 13, 2010 at 0:50

20 votes

Accepted

Divisibility in the homotopy groups of spheres?

answered Nov 25, 2019 at 3:52

17 votes

The most outrageous (or ridiculous) conjectures in mathematics

answered Jan 21, 2017 at 1:05

17 votes

An abstract nonsense proof of the Hurewicz theorem

answered Oct 11, 2017 at 2:47

14 votes

Teaching Steenrod Operations

answered Nov 2, 2017 at 18:18

14 votes

Proof synopsis collection

answered Oct 28, 2010 at 0:03

13 votes

Accepted

In a fibration, can a deformation retraction of the base be lifted to the total space?

answered Aug 14, 2014 at 1:24

13 votes

Why should one still teach Riemann integration?

answered Jan 21, 2011 at 20:52

13 votes

What is the intuition behind the Freudenthal suspension theorem?

answered Feb 23, 2011 at 20:14

12 votes

Why does homotopy behave well with respect to fibrations and homology with respect to cofibrations?

answered Feb 24, 2011 at 21:30

12 votes

Counterexamples in algebraic topology?

answered Feb 14, 2011 at 1:44

11 votes

Categories First Or Categories Last In Basic Algebra?

answered Oct 4, 2010 at 21:04

11 votes

Collecting proofs that finite multiplicative subgroups of fields are cyclic

answered Dec 3, 2016 at 1:09

11 votes

Accepted

"Economic" CW-structure for Eilenberg-MacLane spaces?

answered Sep 6, 2014 at 17:20

11 votes

Why do bees create hexagonal cells ? (Mathematical reasons)

answered Jun 6, 2020 at 18:37

Stack Exchange Network

127 Answers

Nontrivial theorems with trivial proofs

Why do we teach calculus students the derivative as a limit?

Can a subset of the plane have nontrivial $H_2$ or $\pi_2$?

Can a mathematical definition be wrong?

What are some noteworthy "mic-drop" moments in math?

In a topological space if there exists a loop that cannot be contracted to a point does there exist a simple loop that cannot be contracted also?

Is every real n-manifold isomorphic to a quotient of $\mathbb{R}^n$?

Suspension of a topological space

Main statement as theorem or corollary

The role of the mean value theorem (MVT) in first-year calculus

Interesting Calculus Questions/Exercises

Why is it so hard to compute $\pi_n(S^n)$?

Image of a map on cohomology rings

Homotopy equivalent Postnikov sections but not homotopy equivalent

Whitehead theorem for cohomotopy

Advantages of working with CW complexes/spaces over Kan complexes/simplicial sets?

Divisibility in the homotopy groups of spheres?

The most outrageous (or ridiculous) conjectures in mathematics

An abstract nonsense proof of the Hurewicz theorem

Teaching Steenrod Operations

Proof synopsis collection

In a fibration, can a deformation retraction of the base be lifted to the total space?

Why should one still teach Riemann integration?

What is the intuition behind the Freudenthal suspension theorem?

Why does homotopy behave well with respect to fibrations and homology with respect to cofibrations?

Counterexamples in algebraic topology?

Categories First Or Categories Last In Basic Algebra?

Collecting proofs that finite multiplicative subgroups of fields are cyclic

"Economic" CW-structure for Eilenberg-MacLane spaces?

Why do bees create hexagonal cells ? (Mathematical reasons)