9. Other kinds of simple selbri

The following cmavo are discussed in this section:

```     go'i    GOhA                repeats the previous bridi
du      GOhA                equality
nu'a    NUhA                math operator to selbri
moi     MOI                 changes number to ordinal selbri
mei     MOI                 changes number to cardinal selbri
nu      NU                  event abstraction
kei     KEI                 terminator for NU
```
So far we have only discussed brivla and tanru built up from brivla as possible selbri. In fact, there are a few other constructions in Lojban which are grammatically equivalent to brivla: they can be used either directly as selbri, or as components in tanru. Some of these types of simple selbri are discussed at length in Chapter 7, Chapter 11, and Chapter 18; but for completeness these types are mentioned here with a brief explanation and an example of their use in selbri.

The cmavo of selma'o GOhA (with one exception) serve as pro-bridi, providing a reference to the content of other bridi; none of them has a fixed meaning. The most commonly used member of GOhA is probably “go'i”, which amounts to a repetition of the previous bridi, or part of it. If I say:

```9.1)   la djan. klama le zarci
John goes-to the market.
```
you may retort:
```9.2)   la djan. go'i troci
John [repeat last] are-a-tryer
John tries to.
```
Example 9.2 is short for:
```9.3)   la djan. klama be le zarci be'o troci
John is-a-goer (to the market) type-of trier.
```
because the whole bridi of Example 9.1 has been packaged up into the single word “go'i” and inserted into Example 9.2.

The exceptional member of GOhA is “du”, which represents the relation of identity. Its place structure is:

```             x1 is identical with x2, x3, ...
```
for as many places as are given. More information on selma'o GOhA is available in Chapter 7.

Lojban mathematical expressions (mekso) can be incorporated into selbri in two different ways. Mathematical operators such as “su'i”, meaning “plus”, can be transformed into selbri by prefixing them with “nu'a” (of selma'o NUhA). The resulting place structure is:

```             x1 is the result of applying (the operator) to arguments x2, x3, etc.
```
for as many arguments as are required. (The result goes in the x1 place because the number of following places may be indefinite.) For example:
```9.4)   li vo nu'a su'i li re li re
The-number 4 is-the-sum-of the-number 2 and-the-number 2.
```
A possible tanru example might be:
```9.5)   mi jimpe tu'a loi nu'a su'i nabmi
I understand something-about the-mass-of is-the-sum-of problems.
```

More usefully, it is possible to combine a mathematical expression with a cmavo of selma'o MOI to create one of various numerical selbri. Details are available in Chapter 18. Here are a few tanru:

```9.6)   la prim. palvr. pamoi cusku
Preem Palver is-the-1-th speaker.
Preem Palver is the first speaker.

9.7)   la an,iis. joi la .asun. bruna remei
Anyi massed-with Asun are-a-brother type-of-twosome.
Anyi and Asun are two brothers.
```

Finally, an important type of simple selbri which is not a brivla is the abstraction. Grammatically, abstractions are simple: a cmavo of selma'o NU, followed by a bridi, followed by the elidable terminator “kei” of selma'o KEI. Semantically, abstractions are an extremely subtle and powerful feature of Lojban whose full ramifications are documented in Chapter 11. A few examples:

```9.8)   ti nu zdile kei kumfa
This is-an-event-of amusement room.
This is an amusement room.
```
Example 9.8 is quite distinct in meaning from:
```9.9)   ti zdile kumfa
This is-an-amuser room.
```
which suggests the meaning “a room that amuses someone”.