Branching as State Updating

Figure 1(a) is a control oriented form. The recursive variables represent states of a transition system this example has just one state, FSN. The formal parameters I, S, and 0 stand for for input, internal data state, and output, respectively. A state transition involves advancing the input history, updating the state, and performing an output action. The uninterpreted hd, tl, and append operations suggests a model of I/O as list access operations. Condition (P I S) leads to an unspecified branch (T I S 0). For this article, assume T denotes termination, (T 1 SO) 0. 

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