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the grammar



I was thinking about the grammar last night, in particular in reference to
the new changes.  I was giving some thought to the change which makes "cu"
optional rather than elidable.  At first, I thought it made eminent sense.
It would cause a shift-reduce conflict, but that's okay, since at least
YACC handles those by shifting, which is what we want.  But then I realized
that this can lead to trouble.  If "cu" is optional, then that means that
the sentence "le mlatu klama" is grammatical.  The usual reading of it
would be as a sumti, "the cat-like comer."  Since a bare sumti isn't a
grammatical utterance (is it?) the only possible reading is "le mlatu <cu>
klama," "the cat comes."  OK, now we have a break from the accepted reading
caused by the parser, but that's not a real biggie.  Yet.

The trouble comes with something like this:

le mlatu klama le ctuca cukta
the cat  come  the teacher book.

With "cu" mandatory, this utterance is ungrammatical, as it is just a bare
pair of sumti.  With "cu" elidable, things are murky, since we haven't
formalized elidability, but we "know" that it's not elidable in this case,
so we know what it should be.  With "cu" optional, this sentence is clearly
grammatical.  Trouble is, it's *ambiguous* (there, I said it.  Lojban's
bugbear word).  It's either:

le mlatu <cu> klama le ctuca cukta
the cat comes to the teach-book

Or:

le mlatu klama le ctuca <cu> cukta
the cat-comer [to the] teacher comes   (SOV order.)

You can mandate when elision is permissible (and presumably will at some
point), but once you make the change in the grammar, without some snazzy
rules the parser/generator is free to do as it pleases.  YACC will pass
that "sentence" as a valid utterance.  That means it's not a pair of sumti.
So it's a bridi/jufra.  There are two choices.  Which will you take?  This
is *syntactic* ambiguity.  I guess there'll be some disambiguation rule
like right-branching or something, or preference to SVO order, but that
seems contrary to what the parser is about (though I know similar rules are
used to disambiguate other Lojban constructions, e.g. tanru).

Does this make sense?  Do these little, usually incorrect comments of mine
get on people's nerves and make me look silly overmuch?  Sorry if they do.

~mark