[lojban] Re: CFG prize challenge question

[Chris Capel <pdf23ds@gmail.com>]

On Tue, Feb 10, 2009 at 11:23, Jorge Llambías <jjllambias@gmail.com> wrote:
> OK, let me try a different approach, because I really don't understand
> how this formalism is supposed to work. Suppose we have this small
> grammar with three elidable terminators VAU, KU and KEI:
>
> sentence = [terms [CU]] selbri [terms] /VAU/
>
> terms = [terms] sumti
>
> sumti = KOhA | LE selbri /KU/
>
> selbri = [selbri] tanru-unit
>
> tanru-unit = BRIVLA | NU sentence /KEI/
>
> How many start and terminator tokens do we need (if there is a small
> number, what are they, if there are too many to list, what are some
> examples) and what is it that blows up when moving from the
> non-elidable to the elidable case?

You'd need three pairs of tokens, for sentence/vau, le/ku, and nu/kei.
Actually, maybe five. KOhA and BRIVLA probably need to be represented
explicitly so that elided terminators before them don't eat following
subphrases when they're not supposed to. Their terminators would never
be elided.

So making 1=sentence, 2 = le, 3 = KOhA, 4 = nu, 5 = BRIVLA, the
allowable nestings (parent--child) would be 1--2, 1--3, 2--4, 2--5,
4--1.

The blowup isn't actually represented in this part of the system--I
have other parts representing CFG productions and their correspondence
to phrases. The blowup is in the minimum number of productions in the
CFG necessary to parse a given set of tokens and their nestings.

Chris Capel
-- 
"What is it like to be a bat? What is it like to bat a bee? What is it
like to be a bee being batted? What is it like to be a batted bee?"
-- The Mind's I (Hofstadter, Dennet)


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