randomSubSimplicialComplex -- Create a random sub-simplicial complex

i1 : setRandomSeed(currentTime());

i2 : K = randomAbstractSimplicialComplex(4)

o2 = AbstractSimplicialComplex{-1 => {{}}     }
                               0 => {{2}, {3}}
                               1 => {{2, 3}}

o2 : AbstractSimplicialComplex

i3 : J = randomSubSimplicialComplex(K)

o3 = AbstractSimplicialComplex{-1 => {{}}     }
                               0 => {{2}, {3}}
                               1 => {{2, 3}}

o3 : AbstractSimplicialComplex