For the calculation in the natural language on line, it is necessary to introduce several formulas as follows:  σ 1) W2(σ 2) …Wk(σ k) We now describe an example to illustrate the application of Theorem 1. δ is defined as follows:  In this paper, we have considered some basic probabilistic models of computation by inputting strings of words, and some new conclusions have been discovered.
we have studied PFAs with input strings of words, and verified that PFAs computing strings of words can be implemented by means of calculating strings of symbols.