Superadditivity
（重定向自Superadditive function）
In mathematics, a sequence { an }, n ≥ 1, is called superadditive if it satisfies the inequality
for all m and n. The major reason for the use of superadditive sequences is the following lemma due to Michael Fekete.
Lemma: (Fekete) For every superadditive sequence { an }, n ≥ 1, the limit lim an/n exists and is equal to sup an/n. (The limit may be positive infinity, for instance, for the sequence an = log n!.)