Re: Some things about lojban

[wetblu!uunet!math.ucla.edu!jimc]

> Date:  Mon, 14 May 90 16:14:32 -0400 (EDT)
> To:  lojban-list%snark@uunet.UU.NET
> From:  Yary Richard Phillip Hluchan <yh0a+@andrew.cmu.edu>
> Subject:  Some things about lojban
   
> The mailing mentioned that there was some trouble with representing
> mathematical concepts, but there was no description of the current
> method.  Could you mail me a copy of the math grammar?

Just thought I'd mention this on the list: <lojbab> says that there
will be a review of MEX (math expressions) at Logfest, and I've almost
finished putting together a brief demo of -gua!spi MEX to show what can
be done with one particular kind of MEX grammar: not to have any! 
Functionals (like plus and derivative) take arguments using the same
syntax as is used everywhere else in the language.  In -gua!spi this
works well, though I'm not 100% sure it's best for Lojban.  In fact,
the requirement for default articles to make MEX compact was a major
influence on the non-MEX design of -gua!spi.  

I'll be sending it in to <lojbab>; anyone else wanting a copy should
send me mail.  I won't bother everyone with it since it isn't Lojban. 

> One big problem that I remember- and it would take a lot of work to fix-
> is lojban's use of the postfix grammar.  

Actually this isn't quite accurate.  In Old Loglan and in Lojban it has
always been legal to put all the arguments after the main phrase predicate.
The Institute grammar went to a lot of effort to allow just zero or one
argument before the predicate (neglecting "shifted arguments", which nobody
liked or used), but I found that the grammar was self-consistent with
arbitrarily many pre-arguments, and I believe (not sure) that Lojban
includes this feature.  Thus the main predicate can come before, among
or after the arguments, decorations and modal phrases.  

Since my native language is English I usually do Subject-Verb-Object in
the main phrase, but frequently, for style reasons, I will shift the
main predicate wherever I feel like putting it.  In an infinitive
(abstraction) I use post-arguments almost without exception.  

I interpreted the Old Loglan grammar as allowing arguments to have
pre-arguments, i.e. "le mi hasfa" means exactly the same as "le hasfa
je mi" because in both cases "mi" occpies the second case of "hasfa". 
(Not that JCB interpreted it this way...)  Similarly, JCB couldn't
manage to make this illegal: "le la kristoforo kolon botsu"
(Christopher Columbus' boat).  But obviously the prefix position for
the main word is much less ugly and much easier to understand. I don't
know if the current Lojban grammar allows arbitrarily many
pre-arguments in an argument -- I personally think that the grammar is
a lot simpler if you allow it but discourage use of the feature on
stylistic grounds.

> (In fact, I suspect it would be better to represent a block of
> lojban text as a list of trees, with the lujvo at the root of each
> tree... just a hunch).  If it is necessary to store the text as a stack,
> it would be simple to parse from prefix to postfix.

In truth, this is how I represent text in my -gua!spi parser-organizer.
When the tree is spanned, the execution stack of the program ends up with
a pile of recursive calls.  

		-- jimc