摘要
Let A, B be two sets and f: A→ B amap. The iterates fn: An→ B,n = 1,2,... Aredefined inductively by
A1 = A, f1 = f and
An = f-1(An-1 ∩ B), fn = fn-1(f) for n ≥ 2.
Note that A2 = f-1(A1 ∩ B) A = A1 and thus An An-1 A for n ≥ 2.
出处
《数学进展》
CSCD
北大核心
2004年第3期373-374,共2页
Advances in Mathematics（China）
基金
Supported partly by the National Natural Science Foundation of China(No.10371078)and the Natural Science Foundation of Guangdong Province in China(No.984112)
