Two normal forms for link-connector pairs in NCL 3.0

In this paper, we investigate the problem of normal forms for links and connectors in NCL 3.0. We identify two such forms, called the First and Second Normal Forms (NF1 and NF2), in which links and connectors appear in simple terms. We also present normalization procedures (proofs), which show that for every NCL~3.0 program, there is an equivalent program in each of the forms. The mere existence of NF1 and NF2 makes the semantic analysis of programs simpler. Moreover, the symmetry exhibited by these forms suggests that the same principle of arbitrarily ordered evaluation underlies both the evaluation of link conditions and the execution of non-sequential compound actions.