The classification of positive definite unimodular lattices over \(\mathbb{Z} [(1+ \sqrt{21})/2]\)
By combining Siegel's mass formula and Kneser's neighbour lattice method, the author classifies positive definite unimodular lattices of rank 4 over \(\mathbb{Z}[(1+\sqrt{21})/2]\). There are two genera with three classes (in the even case) resp. nine classes (in the genus of the unit form), and representatives of all these classes are computed.
scientific article; zbMATH DE number 1623655