Definition
A recursive transition network (RTN) is a graph-based formalism for context-free grammars. Each network has nodes connected by labeled edges; some edges are labeled with the names of other networks (or the same network), making the formalism recursive. The system traces paths through the network, recursively descending into sub-networks when it encounters a network-name edge.
Why it matters
How it works
Draw a network for each grammatical category (sentence, noun phrase, verb phrase). Nodes are states; edges are labeled with either terminal words or the names of other networks. Tracing a sentence: start at the sentence network's start node, follow edges according to the input, recursively enter sub-networks at network-name edges (pushing the current state), pop back on completion. A sentence is accepted if a trace ends at the start network's accepting state with all input consumed.