Josh Chen's user avatar
Josh Chen's user avatar
Josh Chen's user avatar
Josh Chen
  • Member for 11 years, 7 months
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19 votes
6 answers
8k views

Does a finite commutative ring necessarily have a unity?

13 votes
1 answer
694 views

What exactly does $\frac{\partial(y_1,\dots,y_m)}{\partial(x_1,\dots,x_n)}$ refer to?

11 votes
4 answers
9k views

$\subset$ vs $\subseteq$ when *not* referring to strict inclusion

8 votes
2 answers
632 views

Counterexample: multiplying modules by elements of an ideal vs. taking linear combinations

6 votes
3 answers
2k views

Simultaneous equations, trig functions and the existence of solutions

5 votes
2 answers
225 views

Distributivity in linear monoidal categories

4 votes
1 answer
859 views

Notation - Two adjacent vectors?

4 votes
1 answer
147 views

Is there a name for this "co-dual" vector space?

4 votes
3 answers
167 views

$F[a] \subseteq F(a)?$

4 votes
1 answer
3k views

Is $1-\sin(x)$ a contraction mapping? And is there a sufficient/necessary condition for a real-valued function to be a contraction?

4 votes
2 answers
372 views

Prove that $\cos(x)$ is identically zero using integration by parts

3 votes
0 answers
297 views

Preparation for a foray into noncommutative geometry

3 votes
1 answer
278 views

A differential-functional equation: $f'(f^{-1}(x)) = 1/g(x)$

3 votes
1 answer
238 views

Not understanding this proof in Grünbaum-Shephard's Tilings and Patterns

2 votes
1 answer
361 views

Directly showing $H_0(X, x_0) \cong \widetilde{H}_0(X)$?

1 vote
1 answer
197 views

What does "uniqueness of composition" mean here? (Grünbaum-Shephard's Tilings and Patterns)

1 vote
3 answers
746 views

Finite length $A$-algebras are finitely generated?

1 vote
1 answer
80 views

Suppose I said "$X$ spans $W$"...

1 vote
1 answer
375 views

What's the last step in this proof of the uniqueness of equalizers?