Lojban Reference Grammar: Chapter 7

Chapter 7: Brevity Is The Soul Of Language: Pro-sumti And Pro-bridi

14. The identity predicate: du

The following cmavo is discussed in this section:

   du  GOhA            identity

The cmavo “du” has the place structure:

: x1 is identical with x2, x3, ...

and appears in selma'o GOhA for reasons of convenience: it is not a pro-bridi. “du” serves as mathematical “=”, and outside mathematical contexts is used for defining or identifying. Mathematical examples may be found in Chapter 18.

The main difference between

14.1)    ko'a du le nanmu
it-1 is-identical-to the man

and

14.2)    ko'a mintu le nanmu
it-1 is-the-same-as the man

is this defining nature. Example 14.1 presumes that the speaker is responding to a request for information about what “ko'a” refers to, or that the speaker in some way feels the need to define “ko'a” for later reference. A bridi with “du” is an identity sentence, somewhat metalinguistically saying that all attached sumti are representations for the same referent. There may be any number of sumti associated with “du”, and all are said to be identical.

Example 14.2, however, predicates; it is used to make a claim about the identity of “ko'a”, which presumably has been defined previously.

Note: “du” historically is derived from “dunli”, but “dunli” has a third place which “du” lacks: the standard of equality.