This webpage answers questions about A2.
chart(4) predicate? I don't think you
mentioned it on the handout and towards the end you said: "as
well as chart parser atoms called chart(4)".
chart(4) is an atom, not a predicate. It's meant to
store the chart parser entries that are created as the chart
parsing algorithm progresses. The fields for it are the POS
non-terminal rule being completed, the beginning and end
positions for the completed portion of this non-terminal, and
the POS tags that it still needs to be completed.
You are welcome to modify the code to create chart parser entries in your own way. I simply offer this implementation of the chart entries as a suggestion.
analyseChart predicate? You are using
it in main.pl but I don't see it defined any place
else. Do we have to define it?
analyseChart takes in the list of the words of the
sentence, and scans the chart entries to report on the sentences
that got parsed from this sentence. It uses
write(1) to tell the user how many sentences were
parsed, and how many used all the words in the sentence.
I haven't provided you with this predicate, so you'll have to create it on your own. Here's a little code snippet, to help you along your way:
analyseChart(WordList) :-
length(WordList, TotalLength),
findall(EndPosition, chart(sentence, 0, EndPosition, []), EndPositionList),
length(EndPositionList, SentenceCount),
delete(EndPosList, TotalLength, InvalidPositionList),
length(InvalidPositionList, InvalidTotal),
ValidTotal is SentenceCount - InvalidTotal,
Enjoy :)
semantics.pl I see "analyseSemantics"
predicates but I dont think they are being called anyplace else
like in makeQuery etc. Do we have to call these?
Unlike analyseChart, this is a predicate that I
have given you, but haven't told you where it might be
used. You'll find that it will come in handy when your parse
tree has been created, and you wish to extract the branch of the
tree that corresponds to a particular part-of-speech, specified
in the first parameter of analyseSemantics