sentences:  Baumslag–Solitar group
  
  In the mathematical field of group theory, the Baumslag–Solitar groups are examples of two-generator one-relator groups that play an important role in combinatorial group theory and geometric group theory as (counter)examples and test-cases.They are given by the group presentation
  
  For each integer and , the Baumslag–Solitar group is denoted .