Grammar Engineering Frequently Asked Questions

Looking at the parse chart, it seems that I do have an edge that spans the whole chart (accounts for all the words), but the LKB still says no parses found. What might be going on?

If you have an edge that spans the whole input string, but the LKB still says “no parses found”, the problem probably lies with the root condition. There are two subcases:

  • Your root condition is correct, and your spanning edge is inconsistent with it. For example, say your root condition requires that the the SUBJ value be empty, but your spanning edge has a non-empty SUBJ value. (This could come up if you were working on sentences with null or pro-dropped subjects. If your optional subject rule wasn’t firing, you would have an edge for the whole string (verb plus object, say), but it would not be an acceptable complete parse.
  • Another possibility is that there is a syntax error in your root condition. In this case, the grammar will still load, but the root condition won’t be loaded. (There is an error printed to the LKB top window, but it probably scrolled off the top.) If there is no root condition loaded, nothing will parse. (If you have multiple root conditions and one has a syntax error in it, then only sentences with parses matching error-free root conditions will parse.)
  • Yet a third possibility is that you have two (or more) entries with the identifier root. In this case, only the last one is retained by the system.

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Last update: 2023-06-30 by EricZinda [edit]