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Logical Structure vs. Syntactic Structure



I waited a couple days to respond to this in order to think.
The ramifications of the issues you raise are enormous--they
cast into doubt the basic syntax I have mapped out thus far 
for my conlang, as well as the claims of rigorous logicality 
made for Lojban, which heretofore I had taken more or less 
as an article of faith.  I am not sure I will be able to 
work out all of the issues in this post or even in the 
remainder of this thread, but I can at least name a few 
thoughts in the forefront of my mind at this time.



"And Rosta" <a-rosta@a...> wrote:
> Mike:
"And Rosta" <a-rosta@a...> wrote:
> Mike:
> > --- In engelang@y..., "And Rosta" <a-rosta@a...> wrote:
> > > Mike:
> 
> we could say that an efficient parser requires nonambiguity,
> but one can have nonambiguity without an efficient parsing
> algorithm.

I agree.  In my following remarks, rest assured that I don't 
dispute the points that parsing algorithms can be anywhere 
on the scale between markedly efficient or grossly 
inefficient, and that the former are clearly more 
satisfactory.



> > > A related issue is whether parsing the syntax gives you the
> > > logical structure. For example, although Lojban claims to
> > > have an explicit and unambiguous grammar, this claim is
> > > tantamount to being bogus, or at least fatuous, since all 
> > > the grammar does is generate the set of well-formed word 
> > > strings; the structure imposed by the grammar on the word 
> > > strings does not give you the logical structure of the 
> > > sentence. The rules for getting from the lexicosyntactic 
> > > structure to the logical structure have not been created 
> > > yet. (I exaggerate slightly: the grammar does yield predicate-
> > > argument structure, but not much beyond that.) 
> > 
> > It is here that I am a little cloudy.  Can you elaborate a bit 
> > more on the distinction between the logical structure of the 
> > language and the lexicosyntactic structure as you see it?  
> > Since you mentioned Lojban, would it be possible for you to 
> > give an illustration in that language, assuming time permits?
> 
> Well, for example "ro nanmu cu prami lo ninmu" ("every man
> loves a woman") parses with a structure reflecting the
> predicate-argument structure, "[ro nanmu] [cu prami] [lo
> ninmu]" (I am simplifying here, but not gratuitously
> distorting the facts), according to the official grammar.
> So nothing in the grammatical representation reflects the
> quantifier scope, which in this instance is deemed to follow
> from linear order.

Okay, I see your point.  A few issues crowd my mind at once:

(1) While the formal syntax of the particular example you 
give indeed does not formally parallel the logical structure 
it is deemed to represent, nevertheless, the logical 
structure is clearly unambiguously established.  Purely 
speculatively, could we not somehow re-analyze the syntax in 
order to reflect the logical structure?  If so, would such 
a re-analysis satisfy your objection?

(2) Later on in your post, and also in one of kaliputra's posts,
it was alluded that there are some areas in which a logical 
structure can *not* be unambiguously established from Lojban 
syntax.  I have to confess that I am ignorant of these areas; 
I would have thought that by now all known glitches had 
been worked out.  If there are still glitches, then my 
speculation regarding re-analysis in (1) is perhaps moot.  
Rephrasing this thought as a question: in your view, does 
logical non-ambiguity always demand that the synactical 
structure parallel the logical structure?  Or is it possible
to have some sort of verifiably unambiguous mapping between 
the two types of structures, however clunky and inelegant
this may turn out to be?

(3) If indeed it turns out that in order to have a *verifiably*
rigorous mapping between sentence sound and meaning, we are 
required to parallel the logical structure directly in the 
syntax, then I have grave concerns about the effect that such
a requirement would have on the naturalness of the language.
In the example you give, the closest we come to capturing the
logical structure using plain English as opposed to logicians'
jargon is:

- If something is a man, then it loves at least one woman.

Or a bit briefer:

- If it's a man, it's a woman-lover.

It seems to me that any direct predicate structure 
representation will result in a clouding up of the proper
scope.  At the very least, a lot of care will be needed when
using case tags or voice operations to make word order 
changes.  And yet, surely every natlang (of which I know) 
will prefer the simple predicate construction over the 
conditional-subordination construction which seems required.
I am not sure what the solution is.  There seems to be 
drawbacks either way.  This is a trivially simple logical 
expression, and yet already we have a dilemma.

[snip]
 


> The whole point of a grammar is to map sentence-sounds to
> sentence-meanings. Any so-called grammar that doesn't do that 
> is not a grammar, and its claims to be unambiguous are
> hollow.
> 
> It is not asking too much of an engelang that it have a
> real grammar, for, thanks to logicians, we already know and 
> understand the structure of sentence-meanings. So the 
> goal of the loglang inventor is to take logical structures
> as the starting point and work out the most efficient way
> of encoding them so as to satisfy the other design goals.

In my list of goals, I placed at the top logicality, syntactic 
non-ambiguity, and semantic precision, each of which, to me, 
actually represents an aspect of the same overall objective.  
I listed naturalness immediately after these because of my 
sense that the requirements of logicality would inevitably 
somewhat strain naturalness, thus it was important to maximize 
it wherever possible.  Thus, it is interesting to me to see 
how far we have to veer off from natlang norms in order 
to implement verifiably rigorous logicality.


Regards

---   Mike