“…This calculation takes about 220 seconds of CPUtime on a 3.1 GHz PC running Linux. [ 4,5 ], [ 4,5 ], [ 4,5 ], [ 4,5 ] ] gap> List(designs,BlockNumbers); [ [ 11 ], [ 10,5 ], [ 10,5 ], [ 10,5 ], [ 10,5 ] ] gap> List(designs,d->Size(AutomorphismGroup(d))); [ 660,6,8,12,120 ] More generally, BlockDesigns can construct subdesigns of a given block design, such that the subdesigns each have the same user-specified properties. Here, a subdesign of ∆ means a block design with the same point set as ∆ and whose block multiset is a submultiset of the blocks of ∆ .…”