Finiteness results for regular definite ternary quadratic forms over Q(root 5)

Abstract

Let o be the ring of integers in a number field. An integral quadratic form over o is called regular if it represents all integers in o that are represented by its genus. In [13,14] Watson proved that there are only finitely many inequivalent positive definite primitive integral regular ternary quadratic forms over Z. In this paper, we generalize Watson's result to totally positive regular ternary quadratic forms over Z[1+root 5/2]. We also show that the same finiteness result holds for totally positive definite spinor regular ternary quadratic forms over Z[1+root 5/2], and thus extends the corresponding finiteness results for spinor regular quadratic forms over Z obtained in [ 1,3].