GAP 4.8.9 installation with standard packages -- copy to your CoCalc project to get it
gap> START_TEST("HAP library"); gap> psi1:= [[1,0,1], [0,-1,0], [0,0,1]];; gap> psi2:= [[1,0,0], [0,1,1], [0,0,1]];; gap> G:=AffineCrystGroupOnLeft([psi1,psi2]);; gap> G:=StandardAffineCrystGroup(G);; gap> Y:=EquivariantEuclideanSpace(G,[1/6,1/3]); Equivariant CW-complex of dimension 2 gap> NumbersOfCellOrbits:=List([0..2],Y!.dimension); [ 2, 3, 1 ] gap> VertexStabilizerOrders:= List([1,2],i->Order(Y!.stabilizer(0,i))); [ 1, 1 ] gap> EdgeStabilizerOrders:= List([1,2,3],i->Order(Y!.stabilizer(1,i))); [ 1, 1, 1 ] gap> FaceStabilizerOrders:=Order(Y!.stabilizer(2,1)); 1 gap> Size(Y!.boundary(2,1)); 6 gap> F:=FundamentalGroupOfQuotient(Y); <fp group of size infinity on the generators [ f1, f2 ]> gap> RelatorsOfFpGroup(F); [ f1^-1*f2*f1^-1*f2^-1 ] gap> STOP_TEST( "tst.tst", 1000 );