5. Dropping the prenex

It isn't really necessary for every Lojban bridi involving variables to have a prenex on the front. In fact, none of the examples we've seen so far required prenexes at all! The rule for dropping the prenex is simple: if the variables appear in the same order within the bridi as they did in the prenex, then the prenex is superfluous. However, any ``ro'' or ``poi'' appearing in the prenex must be transferred to the first occurrence of the variable in the main part of the bridi. Thus, Example 2.3 becomes just:

5.1)  da viska mi
    There-is-an-X-which sees me.
    Something sees me.

5.2)  ro da poi gerku cu vasxu
    For-every X which is-a-dog, it-breathes.
    Every dog breathes.

5.3)  ro da poi prenu ku'o
        de poi gerku ku'o zo'u
            de batci da
    For-every X which is-a-person,
        there-is-a-Y which is-a-dog:
            Y bites X.

The prenex of Example 5.3 is like that of Example 3.4 (but with relative clauses): it notes that the following bridi is true of every person with respect to some dog, not necessarily the same dog for each. But in the main bridi part, the ``de'' appears before the ``da''. Therefore, the true translation is

5.4)  Every person is bitten by some dog (or other).

If we tried to omit the prenex and move the ``ro'' and the relative clauses into the main bridi, we would get:

5.5)  de poi gerku cu batci
        ro da poi prenu
    There-is-a-Y which is-a-dog which-bites
        every Y which is-a-person
    Some dog bites everyone.

Even so, Example 5.3 is most probably false, since some people never experience dogbite. Examples like 5.3 and 4.4 (might there be some dogs which never have breathed, because they died as embryos?) indicate the danger in Lojban of universal claims even when restricted. In English we are prone to say that ``Everyone says'' or that ``Everybody does'' or that ``Everything is'' when in fact there are obvious counterexamples which we are ignoring for the sake of making a rhetorical point. Such statements are plain falsehoods in Lojban, unless saved by a context (such as tense) which implicitly restricts them.

How can we express Example 5.3 in Lojban without a prenex? Since it is the order in which variables appear that matters, we can say:

5.6)  ro da poi prenu cu se batci
        de poi gerku
    Every-X which is-a-person is-bitten-by some-Y
        which is-a-dog.

If a variable occurs more than once, then any ``ro'' or ``poi'' decorations are moved only to the first occurrence of the variable when the prenex is dropped. For example,

5.7)  di poi prenu zo'u
        ti xarci di di
    There-is-a-Z which is-a-person :
        this-thing is-a-weapon for-use-against-Z by-Z
    This is a weapon for someone to use against
        himself/herself.

5.8)  ti xarci di
        poi prenu ku'o di
    This-thing is-a-weapon-for-use-against
        some-Z which is-a-person by-Z.