摘要

In this paper, we give a simple construction method of positive definite unimodular lattices with trivial automorphism groups (i.e., the tri-diagonal matrix method), and obtain odd positive definite unimodular lattices of dimensions 29 <= n <= 42 and even positive definite unimodular lattices of dimensions n = 32, 40 with trivial automorphism groups. Combining these with Bannai's and Bacher and Venkov's results we obtain that there exists a unimodular lattice with a trivial automorphism group if and only if the dimension n > 28.

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