Complex sentence: In mathematics, a group is a set of elements together with an operation that combines any two of its elements to form a third element also in the set while satisfying four conditions called the group axioms, namely closure, associativity, identity and invertibility.
Split into simpler sentences: In mathematics, a group is a set of elements together with an operation that combines any two of its elements to form a third element also in the set. To qualify as a group, the set and the operation must satisfy four conditions called the group axioms, namely closure, associativity, identity and invertibility.