_LR := rec < recformat< F: GrpFP, AI: SeqEnum, G: GrpMat > |
      F := FreeGroup(2) >;
_LR`AI := [ [a^-1, a*b*b*a*b*a*b*b] ] where a is (_LR`F).1 where b is (_LR`F).2;
//two constituents interchanges by _LR`AI[1]

_LR`G :=
MatrixGroup<2, ext<K|Polynomial(K, [1,1,1,1,1])> where K is RationalField() |
[[-1,0,-1,-1],[0,0,-1,1],[
0,0,-1,1],[1,0,1,1]],
[[0,0,0,0],[0,-1,0,0],[
-1,-1,-1,-1],[-1,0,0,0]]>;

return _LR;
