Parsing Issues

Decisions

• Left-to-right, right-to-left, and head-first
• Bottom-up parsing
  • Parsing driven by the lexicon
  • Rules indexed by right-hand sides (daughters or phonology)
  • Problem with empty categories
  • Non-determinism when right-hand side (daughters or phonology) of more than one rule or lexical entry matches
• Top-down parsing
  • Parsing driven by the grammar
  • Rules indexed by left-hand sides (synsems)
  • Non-determinism when left-hand side (synsem) of more than one rule or lexical entry matches
  • Problems with left recursion (in left-to-right parsing)
• Parsing as search: depth-first, breadth-first and combinations

Storage of Intermediate Results

• Why
  • Saves time spent reparsing
    • They the saw the nurses report.
      The structure of the nurses is the same, whether or not it is the object of saw.
  • Efficient way of representing multiple parses
    • Phyllis read the book on the volcano.
  • Permits representing partial parses
    • The mischievous boy fleered from the front row.
• Chart parsing as a way to parse while saving intermediate results

[L645 Syllabus]