Simple (mathematics)
In group theory
Simple group: A nontrivial group that has only two normal subgroups: the whole group and the trivial subgroup.
Related terms: Almost simple group, quasisimple group, characteristically simple group, simple algebraic group
Term variations: Groupprops:Category:Variations of simplicity
Primary subject wiki entry: Groupprops:Simple group
Also located at: Wikipedia:Simple group, Mathworld:SimpleGroup, Springer Online Reference Works
In noncommutative ring theory
Simple ring: A nonzero unital ring in which the only two-sided ideals are the whole ring and the zero ideal.
Primary subject wiki entry: Noncommutative:Simple ring
In topology
Simple space: A path-connected space with Abelian fundamental group whose induced action on all higher homotopy groups is trivial.
Primary subject wiki entry: Topospaces:Simple space