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

9. Interval properties: TAhE and “roi”

The following cmavo are discussed in this section:

di'i    TAhE    regularly
na'o    TAhE    typically
ru'i    TAhE    continuously
ta'e    TAhE    habitually

di'inai TAhE    irregularly
na'onai TAhE    atypically
ru'inai TAhE    intermittently
ta'enai TAhE    contrary to habit

roi ROI “n” times
roinai  ROI other than “n” times

ze'e    ZEhA    whole time interval
ve'e    VEhA    whole space interval    

Consider Lojban bridi which express events taking place in time. Whether a very short interval (a point) or a long interval of time is involved, the event may not be spread consistently throughout that interval. Lojban can use the cmavo of selma'o TAhE to express the idea of continuous or non-continuous actions.

✥9.1  mi puzu ze'u
I [past] [long distance] [long interval]
    am-a-school-attendee (pupil).
Long ago I attended school for a long time.

probably does not mean that I attended school continuously throughout the whole of that long-ago interval. Actually, I attended school every day, except for school holidays. More explicitly,

✥9.2  mi puzu ze'u di'i
I [past] [long distance] [long interval] [regularly]
Long ago I regularly attended school for a long time.

The four TAhE cmavo are differentiated as follows: “ru'i” covers the entirety of the interval, “di'i” covers the parts of the interval which are systematically spaced subintervals; “na'o” covers part of the interval, but exactly which part is determined by context; “ta'e” covers part of the interval, selected with reference to the behavior of the actor (who often, but not always, appears in the x1 place of the bridi).

Using TAhE does not require being so specific. Either the time direction or the time interval or both may be omitted (in which case they are vague). For example:

✥9.3  mi ba ta'e klama le zarci
I [future] [habitually] go-to the market.
I will habitually go to the market.
I will make a habit of going to the market.

specifies the future, but the duration of the interval is indefinite. Similarly,

✥9.4  mi na'o klama le zarci
I [typically] go-to the market
I typically go/went/will go to the market

illustrates an interval property in isolation. There are no distance or direction cmavo, so the point of time is vague; likewise, there is no interval cmavo, so the length of the interval during which these goings-to-the-market take place is also vague. As always, context will determine these vague values.

“Intermittently” is the polar opposite notion to “continuously”, and is expressed not with its own cmavo, but by adding the negation suffix “-nai” (which belongs to selma'o NAI) to “ru'i”. For example:

✥9.5  le verba ru'inai cadzu le bisli
The child [continuously-not] walks-on the ice.
The child intermittently walks on the ice.

As shown in the cmavo table above, all the cmavo of TAhE may be negated with “-nai”; “ru'inai” and “di'inai” are probably the most useful.

An intermittent event can also be specified by counting the number of times during the interval that it takes place. The cmavo “roi” (which belongs to selma'o ROI) can be appended to a number to make a quantified tense. Quantified tenses are common in English, but not so commonly named: they are exemplified by the adverbs “never”, “once”, “twice”, “thrice”, … “always”, and by the related phrases “many times”, “a few times”, “too many times”, and so on. All of these are handled in Lojban by a number plus “-roi”:

✥9.6  mi paroi klama le zarci
I [one time] go-to the market.
I go to the market once.

✥9.7   mi du'eroi klama le zarci
I [too-many times] go-to the market.
I go to the market too often.

With the quantified tense alone, we don't know whether the past, the present, or the future is intended, but of course the quantified tense need not stand alone:

✥9.8  mi pu reroi klama le zarci
I [past] [two times] go-to the market.
I went to the market twice.

The English is slightly over-specific here: it entails that both goings-to- the-market were in the past, which may or may not be true in the Lojban sentence, since the implied interval is vague. Therefore, the interval may start in the past but extend into the present or even the future.

Adding “-nai” to “roi” is also permitted, and has the meaning “other than (the number specified)”:

✥9.9  le ratcu reroinai citka le cirli
The rat [twice-not] eats the cheese.
The rat eats the cheese other than twice

This may mean that the rat eats the cheese fewer times, or more times, or not at all.

It is necessary to be careful with sentences like ✥9.6 and ✥9.8, where a quantified tense appears without an interval. What ✥9.8 really says is that during an interval of unspecified size, at least part of which was set in the past, the event of my going to the market happened twice. The example says nothing about what happened outside that vague time interval. This is often less than we mean. If we want to nail down that I went to the market once and only once, we can use the cmavo “ze'e” which represents the “whole time interval”: conceptually, an interval which stretches from time's beginning to its end:

✥9.10    mi ze'e paroi klama le zarci
I [whole interval] [once] go-to the market.

Since specifying no ZEhA leaves the interval vague, ✥9.8 might in appropriate context mean the same as ✥9.10 after all — but ✥9.10 allows us to be specific when specificity is necessary.

A PU cmavo following “ze'e” has a slightly different meaning from one that follows another ZEhA cmavo. The compound cmavo “ze'epu” signifies the interval stretching from the infinite past to the reference point (wherever the imaginary journey has taken you); “ze'eba” is the interval stretching from the reference point to the infinite future. The remaining form, “ze'eca”, makes specific the “whole of time” interpretation just given. These compound forms make it possible to assert that something has never happened without asserting that it never will.

✥9.11    mi ze'epu noroi klama le zarci
I [whole interval] [past] [never] go-to the market.
I have never gone to the market.

says nothing about whether I might go in future.

The space equivalent of “ze'e” is “ve'e”, and it can be used in the same way with a quantified space tense: see c10-§11 for an explanation of space interval modifiers.