[lojban] centripetality: subset vs component

[PILCH Hartmut <phm@A2E.DE>]

> << Also, all addresses can be very well represented as tanrus, and this is
>  likely to occur in conversation
>  
>     day 4 . 
>     which day 4 ?
>     month 5 day 4 .  
>     which month 5 day 4 ?
>     year 1999 month 5 day 4 .
>  
>  In Lojban the default way of doing this is tanru expansion, with a special
>  particle 'be' available for transposition. >>

> None of this looks like it is a natural tanru; it involves names 
> ordescriptions, not predicates.
... 
> I still need a good definition of centrifugal and centripetal, since every 
> time I think I understand them, you give an example that goes exactly against 
> what I just thought I understood (e.g. section-tome is centrifugal, but 
> modifer-modified is cetripetal -- I think -- yet I see these as being 
> essentially the same pattern).

centrifugal / little endian means appending to the right when a
delimitation is asked:

	day 20.

	which "day 20" ?
	
	day 20 of month 5.

or:

	section 828.

	which "section 828" ?

	section 828 of the Civil Law 
	(S 828 BGB)
	
tanru expansion is the addition of specifying attributes that delimit the
set of possibly meant things to a subset.

	a key.

	what key ?

	a box-key.
	
	a key for what kind of box ?
	
	a keybox-key.

	a key for a box of what kind of keys ?

	a boxkeybox-key

	...

In real-life, a certain day is a component of a month, just like a key is
a component of a keybox.

However when I say "the 20th" I don't refer to a certain day, but to a
large set of possible days (keys) in an infinite number of possible
containers (months).  The box-key is thus a subset or the set called
"key".

We have here the notions of subset vs component, which are easy to
confuse.

It is good language design to expand tanru by prepending rather than by
appending, because in address constructions (including places, names,
dates etc) the subset-specifier is usually also a container, and it is a
necessity of human thinking to proceed from the container to the
contained.  Computers can use little-endian, because they are independent
of time.  Human thinking cannot procede in a little-endian manner, because
time has only one direction.  One will always start at a certain container
level and proced inwards to the center from there (centripetal).  If the
language offers only a centrifugal addressing pattern, that can only mean
that the human mind has to make an extra effort at transposing.  Such
efforts are quite normal in natural languages, but the Logical Language
experiment is designed to eliminate them as far as possible.

	renonono nanca [no]mu masti pano djedi
	renonono [no]mu pano 
	nomu masti pano
	nomu pano

etc

I would assume that a direct juxtaposition in a tanru is permissible in
Lojban, because the tanru structure does not imply any specific relations
between the elements except that of delimitation (subset taking).

Thus, although an ordinality specifier might be helpful, it is not
required, and a Chinese-like date is not only possible but in the line of
a consistent Logical Language design.  In dates, brevity is required, and
ordinality specifiers can only be optional.

Apparently these considerations could create a conflict with the design
freeze.  They show an inconsistency in the design of "detri".  The removal
of which will probably have to wait until some official version upgrade of
the "Lojban Standard".  Or is this not the way how Lojban is supposed to
evolve?

-phm