Recursive transition network

A recursive transition network ("RTN") is a graph theoretical tool to represent the rules of a context free grammar. RTNs have application to programming languages, natural language and lexical analysis. Any sentence that is constructed according to the rules of a RTN is said to be "well-formed." The structural elements of a well-formed sentence may also be well-formed sentences by themselves, or they may be simpler structures. This is why RTNs are described as recursive.