The following cmavo is discussed in this section:

Amount abstractions are far more limited than event or property abstractions. They really make sense only if the selbri of the abstracted bridi is subject to measurement of some sort. Thus we can speak of:

because “blueness” could be measured with a colorimeter or a similar device. However,

makes very little sense in either Lojban or English. We simply do not have any sort of measurement scale for being a mother.

Semantically, a sumti with le ni is a number; however, it cannot be treated grammatically as a quantifier in Lojban unless prefixed by the mathematical cmavo mo'e:

Mathematical Lojban is beyond the scope of this chapter, and is explained more fully in Chapter 18.

There are contexts where either property or amount abstractions make sense, and in such constructions, amount abstractions can make use of ce'u just like property abstractors. Thus,

is not the same as

Example 11.37 conveys that the blueness comes and goes, whereas Example 11.38 conveys that its quantity changes over time.

Whenever we talk of measurement of an amount, there is some sort of scale, and so the place structure of ni abstraction selbri is:

Note: the best way to express the x2 places of abstract sumti is to use something like le ni ... kei be. See Example 11.62 for the use of this construction.