Chapter 19: Putting It All Together: Notes on the Structure of Lojban Texts
The following cmavo is discussed in this section:
zo'u ZOhU topic/comment separator
The normal Lojban sentence is just a bridi, parallel to the normal English sentence which has a subject and a predicate:
✥4.1 mi klama le zarci I went to the market
In Chinese, the normal sentence form is different: a topic is stated, and a comment about it is made. (Japanese also has the concept of a topic, but indicates it by attaching a suffix; other languages also distinguish topics in various ways.) The topic says what the sentence is about:
✥4.2 zhe4 xiao1xi2 wo3 zhi1dao le this news I know [perfective] As for this news, I knew it. I've heard this news already.
The wide space in the first two versions of ✥4.2 separate the topic (“this news”) from the comment (“I know already”).
Lojban uses the cmavo “zo'u” (of selma'o ZOhU) to separate topic (a sumti) from comment (a bridi):
✥4.3 le nuzba zu'o mi ba'o djuno The news : I [perfective] know.
✥4.4 mi ba'o djuno le nuzba I [perfective] know the news.
✥4.5 le finpe zo'u citka the fish : eat
Is the fish eating or being eaten? The sentence doesn't say. The Chinese equivalent of ✥4.5 is:
✥4.6 yu2 chi1 fish eat
which is vague in exactly the same way.
Grammatically, it is possible to have more than one sumti before “zo'u”. This is not normally useful in topic-comment sentences, but is necessary in the other use of “zo'u”: to separate a quantifying section from a bridi containing quantified variables. This usage belongs to a discussion of quantifier logic in Lojban (see Chapter 16), but an example would be:
✥4.7 roda poi prenu ku'o su'ode zo'u de patfu da for-all X which-are-persons, there-exists-a-Y such-that Y is the father of X. Every person has a father.
The string of sumti before “zo'u” (called the “prenex”: see Chapter 16) may contain both a topic and bound variables:
✥4.8 loi patfu roda poi prenu ku'o su'ode zo'u de patfu da for-the-mass-of fathers for-all X which-are-persons, there-exists-a-Y such-that Y is the father of X. As for fathers, every person has one.
To specify a topic which affects more than one sentence, wrap the sentences in “tu'e … tu'u” brackets and place the topic and the “zo'u” directly in front. This is the exception to the rule that a topic attaches directly to a sentence:
✥4.9 loi jdini zo'u tu'e do ponse .inaja do djica [tu'u] the-mass-of money : ( [if] you possess, then you want ) Money: if you have it, you want it.
Note: In Lojban, you do not “want money”; you “want to have money” or something of the sort, as the x2 place of “djica” demands an event. As a result, the straightforward rendering of ✥4.8 without a topic is not:
✥4.10 do ponse loi jdini .inaja do djica ri You possess money only-if you desire its-mere-existence
where “ri” means “loi jdini” and is interpreted as “the mere existence of money”, but rather:
✥4.11 do ponse loi jdini .inaja do djica tu'a ri You possess money only-if you desire something-about it
namely, the possession of money. But topic-comment sentences like ✥4.9 are inherently vague, and this difference between “ponse” (which expects a physical object in x2) and “djica” is ignored. See ✥9.3 for another topic/comment sentence.
The subject of an English sentence is often the topic as well, but in Lojban the sumti in the x1 place is not necessarily the topic, especially if it is the normal (unconverted) x1 for the selbri. Thus Lojban sentences don't necessarily have a “subject” in the English sense.