IsRing( domain )
IsRing returns true if the object domain is a ring record,
representing a ring (see Ring Records), and false otherwise.
More precisely IsRing tests whether domain is a ring record (see
Ring Records). So for example a matrix group may in fact be a ring,
yet IsRing would return false.
gap> IsRing( Integers );
true
gap> IsRing( Rationals );
false # 'Rationals' is a field record not a ring record
gap> IsRing( rec( isDomain := true, isRing := true ) );
true # it is possible to fool 'IsRing'
GAP 3.4.4