Efficient syntactic and semantic parsing for ambiguous context-free languages are generally characterized as complex, specialized, highly formal algorithms. In fact, they are readily constructed from straightforward recursive Iransition networks (RTNs). In this paper, we introduce LR-RTNs, and then computationally motivate a uniform progression from basic LR parsing, to Earley's (chart) parsing, concluding with Tomita's parser. These apparently disparate algorithms are unified into a single implementation, which was used to automatically generate all the figures in this paper. 1. I N T R O D U C T I O N Ambiguous context-free grammars (CFGs) are currently used in.
