A Language Processor and a Sample Language

Ayres, 1978

Category: Compilers

Overall Rating

1.9/5 (13/35 pts)

While the paper presents an elegant theoretical concept for factoring ambiguous structures in polynomial space, its dependence on the undecidable framework of general rewrite grammars and its irreversible tie to an obsolete implementation ecosystem make its specific techniques impractical and uncompetitive for modern research challenges.
Despite its obscurity, it offers no concrete, actionable pathway for novel contributions in relevant fields today that isn't better addressed by contemporary, portable methods and theoretical models.

The paper's core innovation lies in its robust and efficient handling of ambiguity within a parsing framework using a structured representation (parsing graph with OR-nodes) that allows for shared substructures and preserves the "locality" of ambiguity across multiple processing passes.
This factored ambiguity representation, combined with a consistent "copy on write" strategy for managing shared data (both in the parsing graph and in the language's data structures), is a powerful concept for dealing with combinatorial explosions of possibilities.
The problem of efficiently representing and processing a large, ambiguous, or multi-modal space of possibilities appears in numerous fields beyond traditional language parsing.
Modern computing power, large-scale memory systems, advanced graph data structures (like property graphs or specialized in-memory databases), and distributed/parallel computing architectures offer powerful tools to implement and scale the parsing graph and multi-pass ambiguity processing concepts discussed.

The core assumption that language processing, particularly semantic interpretation and type checking, is best modeled universally via general rewrite grammars (Type 0) has fundamentally decayed.
The entire system is described as being implemented in MACR0-10 assembly language on a PDP-10. This is tied to a completely obsolete hardware and software ecosystem.
The reliance on Type 0 grammars is a major theoretical limitation. while Type 0 grammars are expressive, their undecidability means there's no general algorithm guaranteed to parse any such grammar.
The system's primary mechanism for handling ambiguity seems focused on representing it compactly (parsing graphs, OR-nodes) rather than providing robust, principled mechanisms for resolving it based on external information or probabilistic likelihoods.

Ignore