Instance newCenter = c.getAsInstance(model, random);
children.add(newCenter);
PFD(D_FOLLOWSPLIT, "first child "+ newCenter);
// substract random vector to center
c2 = c2.substract(r);
newCenter = c2.getAsInstance(model, random);
children.add(newCenter);
PFD(D_FOLLOWSPLIT, "second child "+ newCenter);
return children;