Finite simple group

Symbol-free definition
A group is said to be a finite simple group if it satisfies both these conditions:


 * It is a finite group, viz its order (the cardinality of its underlying set) is a finite integer
 * It is a simple group, viz it has no proper nontrivial normal subgroup

Stronger properties

 * Finite simple non-abelian group

Weaker properties

 * Simple group
 * K-group

Classification problem
The Classification problem is the problem of obtaining a complete description or classification of all the finite simple groups. The Classification Problem has now been solved, viz it has been shown that every finite simple group is one of these:


 * A cyclic group of prime order
 * An alternating group
 * A classical group viz a group obtained as a subquotient of one of the typical linear groups (special linear group, orthogonal group, unitary group, symplectic group)
 * An exceptional group of Lie type
 * A sporadic simple group

Feasibility
A natural number is said to be simple-feasible if it occurs as the order of a simple group. One of the important initial questions in the classification of simple groups is: what are the simple-feasible numbers?

To answer this question, we need a mix of techniques from Sylow theory, representation theory, group actions, and of course basic arguments with subgroups.