Re: [bpfk] FA as a TAG (Was: One cannot refer to inner nodes in Lojban PEG)

On Tue, Apr 7, 2015 at 6:52 PM, Jacob Errington <nictytan@gmail.com> wrote:

I'm making a separate thread out of this because I'm going on a tangent here.

On 7 April 2015 at 15:04, <cowan@ccil.org> wrote:
Terms can have FA or tags equally well, but we don't want to merge
FA with BAI generally, to avoid things like "se fa" and ".i fa bo",
which are nonsense.

I agree that {se fa} has no clear interpretation upon first examination. However, {.i fa bo} can be interpreted like any other {.i TAG bo} construct.

.i broda .i TAG bo brode -> .i broda TAG lo su'u brode

Hence,
.i broda .i fa bo brode -> .i broda fa lo su'u brode

This provides us with another way to do essentially what {la'e di'e} does. For instance,

.i mi pu pensi la'e di'e .i lo mi bruna cu cmalu mutce -> .i mi pu pensi .ifebo lo mi bruna cu cmalu mutce
I was thinking about this: my brother is very short.

There is a certain formal analogy, which may justify such use, but semantically the tag and the FA cases are different.

Taking this idea to the extreme, we can conceive of a somewhat silly higher-order predicate -- call it {brodrfV} for now -- whose x1 is an arbitrary sumti and whose x2 is a nullary predicate supplied with than fV having the value of the x1. We can define {brodrfV} with the following statement.

.i ko'a brodrfV lo du'u broda <=> broda fV ko'a

I'm not sure that's a valid definition. If "ko'e du'u ko'a broda" is true, can I then say that "ko'a brodrfa ko'e" is also true? And what if I now re-express ko'e with an _expression_ that doesn't use "ko'a" as the first argument, is it still true that "ko'a brodrfa ko'e"? The problem is that propositions ("nullary predicates") don't have arguments. Given a proposition p, it is not well defined what its brodrfa should be, its brodrfa seems to be a function of the _expression_ we choose to express the proposition. ma brodrfa lo du'u no da klama? ma brodrfa lo du'u na ku ro da klama?

We can derive some obvious results from this statement.

.i lo brodrfV be lo du'u fV ko'a broda === ko'a
.i fV ko'a broda === .i fi'o brodrfV ko'a broda

This gives us a way to pick out sumti from du'u-abstractions, an otherwise arduous task for the fancylojban programmer/speaker.

It should be an arduous task because du'u-abstractions don't really have sumti. It's the predicates used to construct du'u-abstractions that have sumti, and the same du'u-abstraction could be constructed with different predicates which could have different arguments.

Furthermore, this gives us a way to interpret {se fV}. Since {fV === fi'o brodrfV}, we have {se fV === fi'o se brodrfV}.

For instance
.i lo mi bruna cu cmalu mutce se fe lo du'u mi pu pensi -> mi pu pensi lo du'u lo mi bruna cu cmalu mutce

I've basically hijacked FA to recreate bridi relative clauses.

I'm sure there're plenty of holes in this idea since I cooked it up in just a few minutes. Feel free to come up with weird cases and we can examine them.

It may be workable, but I wouldn't explain it in terms of brodrfV. It would have to be explained in terms of the words being used, not just in terms of their meanings.

Do I want this to be a feature of standard Lojban? Not necessarily. Do I think it's a cool idea? Sure. I hope you do too :)

ie zabna sidbo

mu'o mi'e xorxes