A group is said *SQ-universal* whenever every countable group can be embedded into a quotient of . In some sense, SQ-universality is a “largeness property”. Motivating by this idea, we prove the two following properties: 689 more words

## Tags » Group Theory

#### Some SQ-universal groups

#### The Klein 4-Group

What is the common factor linking book-flips, solitaire, twelve-tone music and the solution of quartic equations? Answer: .

**Symmetries of a Book — or a Brick** 683 more words

#### A theorem of Schur on commutator subgroup

The aim of this note is to prove the following theorem, due to Schur, and to exhibit some corollaries. The proof given here comes from J. 763 more words