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:
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 x2 [ 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:
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:
As usual in Lojban, negated bridi say what is false, and do not say anything about what might be true.