Alex B.
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 Mar5 revised Maximal Unramified Extension of $\mathbb{F}_p((t))$ deleted 157 characters in body Feb17 awarded Nice Question Jan27 comment Abelian torsion group of rational points of an elliptic curve The standard way of doing this is to compute $E(\mathbb{F}_p)$ for a few primes $p$ of good reduction, and to use the fact that the coprime-to-$p$ torsion of $E(\mathbb{Q})$ injects into $E(\mathbb{F}_p)$ Jan26 comment Classifying the irreducible representations of $\mathbb{Z}/p\mathbb{Z}\rtimes \mathbb{Z}/n \mathbb{Z}$ You need to do what I labelled as Exercise 2. Jan25 comment Classifying the irreducible representations of $\mathbb{Z}/p\mathbb{Z}\rtimes \mathbb{Z}/n \mathbb{Z}$ @SvenWirsing: In the specific situation of the OP, they are 1- and $n$-dimensional. In the general situation of my Edit, they are $($dim $\rho\cdot \#$orbit$_H(\chi))$-dimensional. That just follows from the fact that under induction, the dimension of a representation grows by the index of the subgroup that you are inducing from. Jan4 awarded Enlightened Jan4 awarded Nice Answer Dec20 awarded Caucus Dec20 awarded Constituent Nov28 awarded Enlightened Nov28 awarded Nice Answer Nov28 comment Primes of the form $p=a^2-2b^2$. @KCd: thanks Keith, fixed it. Nov28 revised Primes of the form $p=a^2-2b^2$. Corrected, to treat the prime 2 separately Nov7 awarded Yearling Sep2 answered Sum of degrees of irreducible complex characters for certain groups Sep2 comment What are major algebraic number theory attempts, results and progressions toward Goldbach's Conjecture? See this MO question: mathoverflow.net/questions/43434/… Jul25 awarded Enlightened Jul25 awarded Nice Answer Jul4 comment Cosets/ Cyclic group Can you name any coset at all? Can you then find an element of $G$ not in that coset? Jul3 comment What kind of algebraic structure is this Consider the orbit of the unit element under scalar multiplication. That will give you a copy of the scalar field inside the field (use the fact that a field has no non-zero proper ideals). In your example, the subfield consists of scalar matrices. Conversely, whenever you have a field with a subfield, the big field is clearly an algebra under the subfield, just using multiplication in the big field.