Apparently, this user prefers to keep an air of mystery about them.
17 If $\,A^k=0$ and $AB=BA$, then $\,\det(A+B)=\det B$ jan 19 '14
12 Let $G$ be a group of order $360$ and suppose $M$ is a maximal subgroup of $G$ which is isomorphic to $A_5$. Prove that $G$ is isomorphic to $A_6$. jan 2 '14
12 Krull dimension of quotient by principal ideal may 17 '14
9 Existence of prime ideals in rings without identity dec 13 '13
7 Direct proof of non-flatness feb 9 '14