关于无限C~∞-字的性质

On some properties of infinite C~∞-words

给出构造无限C∞-字在求导算子下所有周期点的方法.令Pn(D)={W∈Cω|Dn(W)=W},其中C∞表示所有无限Cω-字的集合,那么|Pn(D)|=2n.

In this note, we gave out the method of constructing all the periodic points of derivation operator,and at the same time prove the formular of counting the number of the elements of P\-n(D)={w∈C~ω|D^n(w)=w} ,i.e.|P\-n(D)|=2~n.