Lojban place structure (was: verbs of eating)

Roger Mills scripsit:

> > While it's in another thread, I'll also mention that "sell" is a
> > four-place verb [in Lojban]: A sells B to C at price D.
> Those certainly capture the essential meanings of buy and sell; but can't D
> "price" in both cases be omitted if it's of no concern/irrelevant/unknown?
Any argument can be omitted if it is of no concern or unknown.  If the
argument is *truly* irrelevant, the fact needs to be indicated with a
"nothing fills this argument place" particle; such things should be
rare.  Thus, for example, there are five places for "go/come":  actor,
destination, origin, route, means; but for "walk" there is only actor,
surface, and limbs.  Walking may often contain a destination and origin,
but not necessarily -- one may walk in circles.

> That's why I don't feel "price" is a core argument of these verbs, any more
> than time ("yesterday") or place ("at an auction") is.
Time and place are indeed *essential* properties metaphysically speaking,
but because they are uniformly essential (except for predicates like
"is identical to") they are not treated as core in Lojban.

The design of Lojban core predicates involves four competing pressures:
metaphysical necessity, convenience, conciseness, and regularity.
A place is metaphysically necessary if it (not its expression, but the
place itself) is essential to the underlying event.  Walking without
an actor, or without a surface, or without legs, just isn't walking:
it's something else altogether.  That does not mean that the surface or
limbs need to be expressed most of the time, but that at the semantic
level they must have valid values.

As for the other three pressures: cenience pushes for more places (it's
convenient to have birthplace and birthdate places on "is born", for
example); conciseness pushes for fewer places (e.g. the typical absence
of date, time, purpose, etc. etc.); regularity pushes a predicate to have
the same number of places as its relatives ("is a lion" has a place for
"species/breed", though all lions are _Panthera leo_, because all the
other animal predicates have this place).

> Let's see, how about "trade, swap"-- that would need
> 1. the person trading "I"
> 2. the thing offered in trade "(my) car"
> 3. the person traded to "Bill"
> 4. the thing received in trade "(Bill's) motorcycle"--
> another 4-place predicate, but #3 is easily omissible.
Just so.  In fact, all of them can be omitted in Lojban:  "I swapped my
horse with Bill" means that I got the obvious thing from Bill, probably
Bill's horse, but context could make it something else.  Likewise,
"I" can be omitted in Lojban if it's obvious enough, as it probably is.
Lojban doesn't have the natlang misfeature whereby certain places *must*
be expressed no matter how obvious they are (neither does Chinese, most
of the time, but in Lojban the rule is quite uniform).

Places are added to predicates by using individual places of other
predicates as prepositions.  Thus, "see" is A sees B under conditions C
(lighting, etc.); there is no native place for the eye with which A sees,
but one can borrow this place from the A place of "is an eye of", which
is A is the eye of B.

--
All Gaul is divided into three parts: the part          John Cowan
that cooks with lard and goose fat, the part            www.ccil.org/~cowan
that cooks with olive oil, and the part that            www.reutershealth.com
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