Let be an abelian group. Prove that is a subgroup of (called the torsion subgroup of ). Give an explicit example where this set is not a subgroup when is non-abelian. A solution: Let . Since the identity is Read More …
An interesting group
I like algebra. MAT5420 was my first mathematics course in Wayne State. Here’s a problem that gave me entertainment this semester. It’s not from MAT5420. It’s an exercise from Serre’s “Trees”. Show that the group is trivial. Here is one way Read More …