gap> R:=ResolutionArtinGroup(D,8);
Resolution of length 8 in characteristic 0 for &lt;fp group on the generators 
[ f1, f2, f3, f4, f5, f6, f7 ]&gt; . 
No contracting homotopy available. 

gap> Size(R);
[ 14, 98, 310, 610, 918, 1326, 2186, 0 ]
