User Alec Teal

32 votes

3 answers

27k views

Vandermonde determinant by induction

asked Oct 14, 2013 at 2:36

15 votes

2 answers

4k views

What does it mean to say a diagram commutes?

asked Apr 14, 2015 at 14:09

12 votes

0 answers

1k views

What does compactness actually mean [duplicate]

asked Feb 25, 2015 at 18:21

9 votes

8 answers

7k views

Cauchy-Schwarz inequality proof (but not the usual one)

asked Jul 11, 2015 at 23:16

8 votes

2 answers

5k views

"Internal" and "external" in maths, and also in vector spaces

asked Dec 11, 2014 at 2:33

7 votes

1 answer

671 views

How is the Chapman-Kolmogorov Equation not a fancy name for matrix multiplication?

asked May 11, 2014 at 4:18

7 votes

4 answers

619 views

I am trying to show $\int^\infty_0\frac{\sin(x)}{x}dx=\frac{\pi}{2}$

asked Dec 2, 2013 at 5:12

6 votes

2 answers

418 views

Cannot follow proof that between two reals there is a rational.

asked Jan 7, 2014 at 4:16

6 votes

1 answer

270 views

Visualising a group structure.

asked Jan 31, 2014 at 14:32

6 votes

2 answers

331 views

Something that isn't continuous can be proven to be continuous (so it is continuous - definitions - but doesn't look it!)

asked Mar 23, 2014 at 14:54

6 votes

3 answers

17k views

What is the operator "capital D" and how can the chain rule be used in this way

asked Feb 2, 2015 at 14:22

6 votes

2 answers

689 views

Definition of a manifold

asked Sep 13, 2015 at 19:41

6 votes

2 answers

708 views

What are "finiteness" and "discreteness" when it comes to compact sets?

asked Mar 9, 2015 at 2:11

6 votes

1 answer

453 views

Proving that every set in the ring generated by all rectangles can be covered by a finite disjoint union of rectangles

asked Mar 16, 2015 at 21:45

5 votes

2 answers

1k views

Are the sets in a basis open in the topology the basis generates?

asked Jan 1, 2015 at 12:53

5 votes

1 answer

821 views

If $f\in A_k(V)$ and $g\in A_l(V)$ show $i_v(f\wedge g)=i_vf\wedge g+(-1)^kf\wedge i_vg$ - I've got the gist, not sure how to write

asked Oct 17, 2014 at 13:00

5 votes

1 answer

797 views

How did the Symmetric group and Alternating group come to be named as such?

asked Mar 26, 2014 at 1:45

5 votes

2 answers

568 views

A variation of how many integer solutions are there for $a+b+...=n$

asked Feb 17, 2014 at 13:53

5 votes

5 answers

6k views

A 2x2 matrix $M$ exists. Suppose $M^3=0$ show that (I want proof) $M^2=0$

asked Oct 13, 2013 at 23:24

5 votes

3 answers

13k views

Why is the Jacobian matrix the transpose of what I would think it'd be/usefully be (total derivative is a synonym) (EDIT: I was a total wally)

asked Aug 1, 2013 at 17:22

4 votes

1 answer

122 views

Is there a faster way (I've found a good one but I want to be sure) - interesting calculus question

asked Aug 30, 2013 at 12:05

4 votes

0 answers

107 views

Chinese Remainder Theorem stuff (but more advanced, certainly derived from)

asked Mar 3, 2014 at 2:08

4 votes

3 answers

648 views

For a 2x2 matrix A satisfying $A^k=I$, compute $e^A$

asked Nov 29, 2014 at 21:08

4 votes

2 answers

3k views

Is there a notation for "open subset"

asked Apr 6, 2015 at 0:15

4 votes

1 answer

249 views

Why can't suspace topologies be the empty set?

asked Dec 31, 2014 at 20:05

3 votes

2 answers

705 views

My proof that an n digit number, times an n digit number can be expressed as a 2n digit number

asked May 23, 2015 at 9:54

3 votes

2 answers

962 views

Convergene of a sequence if and only if limsup and liminf agree

asked Jan 8, 2015 at 2:05

3 votes

1 answer

90 views

Can I show these questions (is a set open or closed WRT metric) a faster way?

asked Jun 8, 2014 at 20:03

3 votes

2 answers

7k views

Continuous functions that pointwise converge to zero, but the integral tending towards infinity.

asked Apr 27, 2014 at 21:33

3 votes

2 answers

73 views

Answer check $\int_{\lvert z\rvert=1}(z-1)^2\lvert dz\rvert$ = $2\pi$

asked Dec 2, 2013 at 4:26

Stack Exchange Network

147 Questions

Vandermonde determinant by induction

What does it mean to say a diagram commutes?

What does compactness actually mean [duplicate]

Cauchy-Schwarz inequality proof (but not the usual one)

"Internal" and "external" in maths, and also in vector spaces

How is the Chapman-Kolmogorov Equation not a fancy name for matrix multiplication?

I am trying to show $\int^\infty_0\frac{\sin(x)}{x}dx=\frac{\pi}{2}$

Cannot follow proof that between two reals there is a rational.

Visualising a group structure.

Something that isn't continuous can be proven to be continuous (so it is continuous - definitions - but doesn't look it!)

What is the operator "capital D" and how can the chain rule be used in this way

Definition of a manifold

What are "finiteness" and "discreteness" when it comes to compact sets?

Proving that every set in the ring generated by all rectangles can be covered by a finite disjoint union of rectangles

Are the sets in a basis open in the topology the basis generates?

If $f\in A_k(V)$ and $g\in A_l(V)$ show $i_v(f\wedge g)=i_vf\wedge g+(-1)^kf\wedge i_vg$ - I've got the gist, not sure how to write

How did the Symmetric group and Alternating group come to be named as such?

A variation of how many integer solutions are there for $a+b+...=n$

A 2x2 matrix $M$ exists. Suppose $M^3=0$ show that (I want proof) $M^2=0$

Why is the Jacobian matrix the transpose of what I would think it'd be/usefully be (total derivative is a synonym) (EDIT: I was a total wally)

Is there a faster way (I've found a good one but I want to be sure) - interesting calculus question

Chinese Remainder Theorem stuff (but more advanced, certainly derived from)

For a 2x2 matrix A satisfying $A^k=I$, compute $e^A$

Is there a notation for "open subset"

Why can't suspace topologies be the empty set?

My proof that an n digit number, times an n digit number can be expressed as a 2n digit number

Convergene of a sequence if and only if limsup and liminf agree

Can I show these questions (is a set open or closed WRT metric) a faster way?

Continuous functions that pointwise converge to zero, but the integral tending towards infinity.

Answer check $\int_{\lvert z\rvert=1}(z-1)^2\lvert dz\rvert$ = $2\pi$