7. Other useful selbri for mekso bridi

So far our examples have been isolated mekso (it is legal to have a bare mekso as a sentence in Lojban) and equation bridi involving ``du''. What about inequalities such as ``x < 5''? The answer is to use a bridi with an appropriate selbri, thus:

7.1)  li xy. mleca li mu
    the-number x is-less-than the-number 5

Here is a partial list of selbri useful in mathematical bridi:

   du      x1 is identical to x2, x3, x4, ...
    dunli       x1 is equal/congruent to x2 in/on
            property/quality/dimension/quantity x3
    mleca       x1 is less than x2
    zmadu       x1 is greater than x2
    dubjavme'a  x1 is less than or equal to x2
                [du ja mleca, equal or less]
    dubjavmau   x1 is greater than or equal to x2
                [du ja zmadu, equal or greater]
    tamdu'i     x1 is similar to x2
                [tarmi dunli, shape-equal]
    turdu'i     x1 is isomorphic to x2
                [stura dunli, structure-equal]
    cmima       x1 is a member of set x2
    gripau      x1 is a subset of set x2
                [girzu pagbu, set-part]
    na'ujbi     x1 is approximately equal to
                [namcu jibni, number-near]
    terci'e     x1 is a component with function x2
            of system x3
Note the difference between ``dunli'' and ``du''; ``dunli'' has a third place that specifies the kind of equality that is meant. ``du'' refers to actual identity, and can have any number of places:
7.2)  py. du xy.boi zy.
    ``p'' is-identical-to ``x'' ``z''
    p = x = z

Lojban bridi can have only one predicate, so the ``du'' is not repeated.

Any of these selbri may usefully be prefixed with ``na'', the contradictory negation cmavo, to indicate that the relation is false:

7.3)  li re su'i re na du li mu
    the-number 2 + 2 is-not equal-to the-number 5.
    2 + 2 ½ 5

As usual in Lojban, negated bridi say what is false, and do not say anything about what might be true.