“…The parameters appearing in the above lists have geometric meaning: basically they encode the base locus of an elliptic pencil on the Hirzebruch surface F 2 , see (20), (21), (22), (23). For example, a + , a − (and similarly b + , b − ) determine the locations of the base points on the fibers of the Hirzebruch surface, see also Figures 4 and 5. In order to state our results, it will be useful to consider some polynomial expressions M, L, A and B of these parameters:…”