NoSign < Main

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---+Grammar Engineering Frequently Asked Questions

---++My grammar loads just fine, but when I try to parse a sentence, it says *"no sign can be constructed for ..."*. What's happening?

This error occurs when the LKB is unable to build an edge for a word
in the input string.  This can happen in at least the following
two scenarios:

   1. The word requires the application of lexical rules, but the constraints on the sequence of lexical rules required to build the word form are not compatible.  To understand this, one need to know the following:  In processing each word, the LKB first runs the spelling change part of the lexical rules only to figure out what the possible stem forms are (while keeping track of the rules that were used).  It then tries to build the words back up, using those lexical rules (perhaps interspersed with the non-spelling-change [or constant] lexical rules).  It is only at this point that the constraints on the lexical rules are consulted.  If there is no way to build the word back up to its input form, the "no sign can be constructed for" error is output, and the word won't appear in the chart.
   1. The word is available only as part of a multi-word lexical entry, and the other required words are not in the input string.  [Confirm this.]

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-- Main.EmilyBender - 31 May 2005
Topic revision: r1 - 2005-05-31 - EmilyBender