Convincing an LR parser to emit fragments?

Hello all,


My work is connected with parsing natural language and in particular with
dealing with undergeneration. That is, what happens when we have some
sentence l that is not in L(g), where g is a grammar attempting to account
for some natural language.


My query concerns the use of LR parsers for dealing with undergeneration.
A chart parser will produce a chart showing the set of partial derivation
sequences that it has constructed. Would it be possible to convince an LR
parser to do likewise? I know that the correct prefix property means that
an LR parser will stop as soon as the sentence extends out of the
language, but this is not what I want: I want the parser to be able to
emit the fragments. I would like to use an LR parser but if I can't
convince it to produce the fragments then I'll have to fall back onto
chart parsing, which is what I would like to avoid.


Thanks


Miles
miles@minster.york.ac.uk
[There's always Earley's algorithm which carries along all of the possible
parses even for ambiguous input. -John]
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