Chapter 10: Imaginary Journeys: The Lojban Space/Time Tense System
The following cmavo are discussed in this section:
pu'o ZAhO inchoative ca'o ZAhO continuitive ba'o ZAhO perfective co'a ZAhO initiative co'u ZAhO cessitive mo'u ZAhO completitive za'o ZAhO superfective co'i ZAhO achievative de'a ZAhO pausative di'a ZAhO resumptive re'u ROI ordinal tense
The cmavo of selma'o ZAhO express the Lojban version of what is traditionally called “aspect”. This is not a notion well expressed by English tenses, but many languages (including Chinese and Russian among Lojban's six source languages) consider it more important than the specification of mere position in time.
The “event contours” of selma'o ZAhO, with their bizarre keywords, represent the natural portions of an event considered as a process, an occurrence with an internal structure including a beginning, a middle, and an end. Since the keywords are scarcely self-explanatory, each ZAhO will be explained in detail here. Note that from the viewpoint of Lojban syntax, ZAhOs are interval modifiers like TAhEs or ROI compounds; if both are found in a single tense, the TAhE/ROI comes first and the ZAhO afterward. The imaginary journey described by other tense cmavo moves us to the portion of the event-as-process which the ZAhO specifies.
It is important to understand that ZAhO cmavo, unlike the other tense cmavo, specify characteristic portions of the event, and are seen from an essentially timeless perspective. The “beginning” of an event is the same whether the event is in the speaker's present, past, or future. It is especially important not to confuse the speaker-relative viewpoint of the PU tenses with the event-relative viewpoint of the ZAhO tenses.
The cmavo “pu'o”, “ca'o”, and “ba'o” (etymologically derived from the PU cmavo) refer to an event that has not yet begun, that is in progress, or that has ended, respectively:
✥10.1 mi pu'o damba I [inchoative] fight. I'm on the verge of fighting.
✥10.2 la stiv. ca'o bacru Steve [continuitive] utters. Steve continues to talk.
✥10.3 le verba ba'o cadzu le bisli The child [perfective] walks-on the ice. The child is finished walking on the ice.
As discussed in c10-§6, the simple PU cmavo make no assumptions about whether the scope of a past, present, or future event extends into one of the other tenses as well. Examples 10.1 through 10.3 illustrate that these ZAhO cmavo do make such assumptions possible: the event in 10.1 has not yet begun, definitively; likewise, the event in 10.3 is definitely over.
Note that in ✥10.1 and ✥10.3, “pu'o” and “ba'o” may appear to be reversed: “pu'o”, although etymologically connected with “pu”, is referring to a future event; whereas “ba'o”, connected with “ba”, is referring to a past event. This is the natural result of the event-centered view of ZAhO cmavo. The inchoative, or “pu'o”, part of an event, is in the “pastward” portion of that event, when seen from the perspective of the event itself. It is only by inference that we suppose that ✥10.1 refers to the speaker's future: in fact, no PU tense is given, so the inchoative part of the event need not be coincident with the speaker's present: “pu'o” is not necessarily, though in fact often is, the same as “ca pu'o”.
The cmavo in Examples 10.1 through 10.3 refer to spans of time. There are also two points of time that can be usefully associated with an event: the beginning, marked by “co'a”, and the end, marked by “co'u”. Specifically, “co'a” marks the boundary between the “pu'o” and “ca'o” parts of an event, and “co'u” marks the boundary between the “ca'o” and “ba'o” parts:
✥10.4 mi ba co'a citka le mi sanmi I [future] [initiative] eat my meal. I will begin to eat my meal. ✥10.5 mi pu co'u citka le mi sanmi I [past] [cessitive] eat my meal. I ceased eating my meal.
Compare ✥10.4 with:
✥10.6 mi ba di'i co'a bajra I [future] [regularly] [initiative] run. I will regularly begin to run.
which illustrates the combination of a TAhE with a ZAhO.
A process can have two end points, one reflecting the “natural end” (when the process is complete) and the other reflecting the “actual stopping point” (whether complete or not). ✥10.5 may be contrasted with:
✥10.7 mi pu mo'u citka le mi sanmi I [past] [completitive] eat my meal. I finished eating my meal.
A process such as eating a meal does not necessarily proceed uninterrupted. If it is interrupted, there are two more relevant point events: the point just before the interruption, marked by “de'a”, and the point just after the interruption, marked by “di'a”. Some examples:
✥10.8 mi pu de'a citka le mi sanmi I [past] [pausative] eat my meal. I stopped eating my meal (with the intention of resuming). ✥10.9 mi ba di'a citka le mi sanmi I [future] [resumptive] eat my meal. I will resume eating my meal.
In addition, it is possible for a process to continue beyond its natural end. The span of time between the natural and the actual end points is represented by “za'o”:
✥10.10 le xirma ca za'o jivna bajra The horse [present] [superfective] compete-type-of runs. The horse keeps on running a race too long.
which means that it ran past the finish line (after the race was over — in most races, the runners do not stop right at the finish line).
An entire event can be treated as a single moment using the cmavo “co'i”:
✥10.11 la djan. pu co'i catra la djim John [past] [achievative] kills Jim. John was at the point in time where he killed Jim.
Finally, since an activity is cyclical, an individual cycle can be referred to using a number followed by “re'u”, which is the other cmavo of selma'o ROI:
✥10.12 mi pare'u klama le zarci I [first time] go-to the store. I go to the store for the first time (within a vague interval).
Note the difference between:
✥10.13 mi pare'u paroi klama le zarci I [first time] [one time] go-to the store. For the first time, I go to the store once.
✥10.14 mi paroi pare'u klama le zarci I [one time] [first time] go-to the store. There is one occasion on which I go to the store for the first time.