Why is the formulation of M(embrane) theory so hard?
55534
Why one-dimensional strings, but not higher-dimensional shells/membranes?
156382
Why is Compactification restricted to Toroids, Calabi-Yau et al?
85398
$\mathsf{ZF}$ is not finitely axiomatizable
13274
Why does \cal{M}_n give “M>”?
156868
Why is finding $M$ eigenvectors on smaller matrix valid?
41069
Justifying $\,\Bbb{Z}[i]/\langle 2\rangle\cong \Bbb{Z}[X]/\langle X^2+1,2\rangle\cong \Bbb{F}_2[X]/\langle X^2+1\rangle$
151581
Prerequisite for Milnor Topology from a Differential Viewpoint
111746
$(A/\mathfrak{a}) \otimes_A M \simeq M / \mathfrak{a}M$ by tensoring the canonical exact sequence.
111703
If $H \leq G$ and $[G:H]! \leq |G|$ then $G$ is not simple
92211
When are $\mathbb Z_m$ and $\mathbb Z_n$ homomorphic?
155750
Why does $\mathbb{C}$ have transcendence degree $\mathfrak{c}$ over $\mathbb{Q}$?
7870
For $M\otimes_R N$, why is it so imperative that $M$ be a right $R$-module and $N$ a left $R$-module?
133238
Why does $\mathrm{Tor}_0^R(M,N)\cong M\otimes_R N$?
130858
How can one find $\mu$?
62832
What is the Killing form of $\mathfrak{gl}_{m}$?
16534
Can $(\Bbb N,\leq)$ have an $\aleph_0$-categorical theory (in a larger language)?
29084
Largest integer that can't be represented as a non-negative linear combination of $m, n = mn - m - n$? Why?