Chapter 10: Imaginary Journeys: The Lojban Space/Time Tense System

16. Tense relations between sentences

The sumti tcita method, explained in c10-§12, of asserting a tense relationship between two events suffers from asymmetry. Specifically,

✥16.1    le verba cu cadzu le bisli
    zu'a le nu le nanmu cu batci le gerku
The child walks-on the ice
    [left] the event-of the man bites the dog.
The child walks on the ice to the left of where
    the man bites the dog.

which specifies an imaginary journey leftward from the man biting the dog to the child walking on the ice, claims only that the child walks on the ice. By the nature of “le nu”, the man's biting the dog is merely referred to without being claimed. If it seems desirable to claim both, each event can be expressed as a main sentence bridi, with a special form of “.i” connecting them:

✥16.2    le nanmu cu batci le gerku
    .izu'abo le verba cu cadzu le bisli
The man bites the dog.
    [Left] the child walks-on the ice.
The  man bites the dog.  To the left, the child
    walks on the ice.

“.izu'abo” is a compound cmavo: the “.i” separates the sentences and the “zu'a” is the tense. The “bo” is required to prevent the “zu'a” from gobbling up the following sumti, namely “le verba”.

Note that the bridi in ✥16.2 appear in the reverse order from their appearance in ✥16.1. With “.izu'abo” (and all other afterthought tense connectives) the sentence specifying the origin of the journey comes first. This is a natural order for sentences, but requires some care when converting between this form and the sumti tcita form.

✥16.2 means the same thing as:

✥16.3    le nanmu cu batci le gerku
    .i zu'a la'edi'u
    le verba cu cadzu le bisli
The man bites the dog.
    [Left] the-referent-of-the-last-sentence
    the child walks-on the ice.
The man bites the dog.
    Left of what I just mentioned,
    the child walks on the ice.

If the “bo” is omitted, the meaning changes:

✥16.4    le nanmu cu batci le gerku
    .i zu'a le verba cu cadzu le bisli
The man bites the dog.
     [Left] the child [something] walks-on the ice.
The man bites the dog. To the left of the child,
    something walks on the ice.

Here the first place of the second sentence is unspecified, because “zu'a” has absorbed the sumti “le verba”.

Do not confuse either ✥16.2 or ✥16.4 with the following:

✥16.5    le nanmu cu batci le gerku
    .i zu'aku le verba cu cadzu le bisli
The man bites the dog.
    [Left] the child walks-on the ice.
The man bites the dog.  Left of me, the child walks
    on the ice.

In ✥16.5, the origin point is the speaker, as is usual with “zu'aku”. ✥16.2 makes the origin point of the tense the event described by the first sentence.

Two sentences may also be connected in forethought by a tense relationship. Just like afterthought tense connection, forethought tense connection claims both sentences, and in addition claims that the time or space relationship specified by the tense holds between the events the two sentences describe.

The origin sentence is placed first, preceded by a tense plus “gi”. Another “gi” is used to separate the sentences:

✥16.6    pugi mi klama le zarci gi mi klama le zdani
[past] I go-to the market [,] I go-to the house.
Before I go to the market, I go to the house.

A parallel construction can be used to express a tense relationship between sumti:

✥16.7    mi klama pugi le zarci gi le zdani
I go-to [past] the market [,] the house.

Because English does not have any direct way of expressing a tense-like relationship between nouns, ✥16.7 cannot be expressed in English without paraphrasing it either into ✥16.6 or else into “I go to the house before the market”, which is ambiguous — is the market going?

Finally, a third forethought construction expresses a tense relationship between bridi-tails rather than whole bridi. (The construct known as a “bridi-tail” is explained fully in Chapter 14; roughly speaking, it is a selbri with any following sumti.) ✥16.8 is equivalent in meaning to ✥16.6 and ✥16.7:

✥16.8    mi pugi klama le zarci gi klama le zdani
I [past] go-to the market [,] go-to the house.
I, before going to the market, go to the house.

In both ✥16.7 and ✥16.8, the underlying sentences “mi klama le zarci” and “mi klama le zdani” are not claimed; only the relationship in time between them is claimed.

Both the forethought and the afterthought forms are appropriate with PU, ZI, FAhA, VA, and ZAhO tenses. In all cases, the equivalent forms are (where X and Y stand for sentences, and TENSE for a tense cmavo):

subordinate: X TENSE le nu Y afterthought coordinate: Y .i+TENSE+bo X forethought coordinate: TENSE+gi X gi Y