This chapter is not about Lojban mathematics, which is explained in Chapter 18, so the mathematical uses of lerfu strings will be listed and exemplified but not explained.
A lerfu string as function name (preceded by ma'o of selma'o MAhO):
Note the boi here to separate the lerfu strings fy and xy.
A lerfu string as subscript (preceded by xi of selma'o XI):
The parentheses are required because ny. lo prenu would be two separate sumti, ny. and lo prenu. In general, any mathematical expression other than a simple number must be in parentheses when used as a quantifier; the right parenthesis mark, the cmavo ve'o, can usually be elided.
All the examples above have exhibited single lerfu words rather than lerfu strings, in accordance with the conventions of ordinary mathematics. A longer lerfu string would still be treated as a single variable or function name: in Lojban,
.abu by. cy. is not the multiplication
“a × b × c” but is the variable
abc
. (Of course, a local convention could be employed that made the value of a variable like
abc
, with a multi-lerfu-word name, equal to the values of the variables
a
,
b
, and
c
multiplied together.)
There is a special rule about shift words in mathematical text: shifts within mathematical expressions do not affect lerfu words appearing outside mathematical expressions, and vice versa.