Chapter 5: “Pretty Little Girls' School”: The Structure Of Lojban selbri

3. Three-part tanru grouping with “bo”

The following cmavo is discussed in this section:

bo  BO  closest scope grouping

Consider the English sentence:

✥3.1  That's a little girls' school.

What does it mean? Two possible readings are:

✥3.2  That's a little school for girls.

✥3.3   That's a school for little girls.

This ambiguity is quite different from the simple tanru ambiguity described in c5-§2. We understand that “girls' school” means “a school where girls are the students”, and not “a school where girls are the teachers” or “a school which is a girl” (!). Likewise, we understand that “little girl” means “girl who is small”. This is an ambiguity of grouping. Is “girls' school” to be taken as a unit, with “little” specifying the type of girls' school? Or is “little girl” to be taken as a unit, specifying the type of school? In English speech, different tones of voice, or exaggerated speech rhythm showing the grouping, are used to make the distinction; English writing usually leaves it unrepresented.

Lojban makes no use of tones of voice for any purpose; explicit words are used to do the work. The cmavo “bo” (which belongs to selma'o BO) may be placed between the two brivla which are most closely associated. Therefore, a Lojban translation of ✥3.2 would be:

✥3.4  ta cmalu nixli bo ckule
That is-a-small girl -- school.

✥3.3 might be translated:

✥3.5  ta cmalu bo nixli ckule
That is-a-small -- girl school.

The “bo” is represented in the literal translation by a hyphen because in written English a hyphen is sometimes used for the same purpose: “a big dog-catcher” would be quite different from a “big-dog catcher” (presumably someone who catches only big dogs).

Analysis of ✥3.4 and ✥3.5 reveals a tanru nested within a tanru. In ✥3.4, the main tanru has a seltau of “cmalu” and a tertau of “nixli bo ckule”; the tertau is itself a tanru with “nixli” as the seltau and “ckule” as the tertau. In ✥3.5, on the other hand, the seltau is “cmalu bo nixli” (itself a tanru), whereas the tertau is “ckule”. This structure of tanru nested within tanru forms the basis for all the more complex types of selbri that will be explained below.

What about ✥3.6? What does it mean?

✥3.6  ta cmalu nixli ckule
That is-a-small girl school.

The rules of Lojban do not leave this sentence ambiguous, as the rules of English do with ✥3.1. The choice made by the language designers is to say that ✥3.6 means the same as ✥3.5. This is true no matter what three brivla are used: the leftmost two are always grouped together. This rule is called the “left-grouping rule”. Left-grouping in seemingly ambiguous structures is quite common — though not universal — in other contexts in Lojban.

Another way to express the English meaning of ✥3.4 and ✥3.5, using parentheses to mark grouping, is:

✥3.7  ta cmalu nixli bo ckule
That is-a-small type-of (girl type-of school).

✥3.8   ta cmalu bo nixli ckule
That is-a-(small type-of girl) type-of school.

Because “type-of” is implicit in the Lojban tanru form, it has no Lojban equivalent.

Note: It is perfectly legal, though pointless, to insert “bo” into a simple tanru:

✥3.9  ta klama bo jubme
That is-a goer -- table

is a legal Lojban bridi that means exactly the same thing as ✥2.8, and is ambiguous in exactly the same ways. The cmavo “bo” serves only to resolve grouping ambiguity: it says nothing about the more basic ambiguity present in all tanru.