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Apr
7
accepted How to recognize adjointness?
Apr
5
accepted What are integrating factors, really?
Mar
16
accepted On proving $n = \sum_{d\mid n}\varphi(d)$
Mar
16
accepted On last digit of 4 consecutive primes less than 10 apart
Mar
16
accepted Is there any advantage to the $a \equiv b\;\;(\mathrm{mod}\;c)$ notation?
Mar
3
accepted Natural uses for the co-product of sets?
Feb
2
accepted Looking for counterexample where $K \not \subset H$ and $[G:K] \neq [H:H\cap K]$
Feb
1
accepted How to prove $\frac{1}{q} \binom{p^k q}{p^k} \equiv 1 \mod p\;\;$?
Jan
19
accepted Why isn't the orbit-stabilizer theorem obvious?
Jan
11
accepted What's the rationale for requiring that a field be a $\boldsymbol{non}$-$\boldsymbol{trivial}$ ring?
Jan
8
accepted Matrix-free proof of $Z(GL_n(F)) = \{\lambda I:\lambda \in F^\times\}$?
Jan
7
accepted Simpler proof of $g\,h\,g^{-1} = h^a \Rightarrow g^n\,h\,g^{-n} = h^{a^n}$
Jan
2
accepted Simple proof that symmetries of regular polyhedron fix its center?
Dec
26
accepted Looking for simpler proof of “well-definedness” of basis subtended by points in “general position”
Dec
25
accepted Is there a standard shorthand for the set $\{0, 1, \dots,k-1,k+1,\dots,n-1,n\}$?
Dec
25
accepted Undergraduate-level intro to homotopy
Dec
25
accepted On “familiarity” (or How to avoid “going down the Math Rabbit Hole”?)
Jul
9
accepted Example of a module for non-mathematicians
Jul
4
accepted Error in book's definition of open sets in terms of neighborhoods?
Jul
2
accepted On the period of the decimal representation of $n$ when $\gcd(n, 10) \neq 1$