English has the concepts of “comparative adjectives” and “superlative adjectives” which can be formed from other adjectives, either by adding the suffixes “-er” and “-est” or by using the words “more” and “most” , respectively. The Lojbanic equivalents, which can be made from any brivla, are lujvo with the tertau zmadu , mleca , zenba , jdika , and traji . In order to make these lujvo regular and easy to make, certain special guidelines are imposed.

We will begin with lujvo based on zmadu and mleca , whose place structures are:

For example, the concept “young” is expressed by the gismu citno , with place structure

The comparative concept “younger” can be expressed by the lujvo citmau (based on the veljvo citno zmadu , meaning “young more-than” ).

The place structure for citmau is

Similarly, in Lojban you can say:

In English, “more” comparatives are easier to make and use than “less” comparatives, but in Lojban the two forms are equally easy.

Because of their much simpler place structure, lujvo ending in -mau and -me'a are in fact used much more frequently than zmadu and mleca themselves as selbri. It is highly unlikely for such lujvo to be construed as anything other than implicit-abstraction lujvo. But there is another type of ambiguity relevant to these lujvo, and which has to do with what is being compared.

For example, does nelcymau mean “X likes Y more than X likes Z” , or “X likes Y more than Z likes Y” ? Does klamau mean: “X goes to Y more than to Z” , “X goes to Y more than Z does” , “X goes to Y from Z more than from W” , or what?

We answer this concern by putting regularity above any considerations of concept usefulness: by convention, the two things being compared always fit into the first place of the seltau. In that way, each of the different possible interpretations can be expressed by SE-converting the seltau, and making the required place the new first place. As a result, we get the following comparative lujvo place structures:

(See Chapter 11 for the way in which this problem is resolved when lujvo aren't used.)

The ordering rule places the things being compared first, and the other seltau places following. Unfortunately the z4 place, which expresses by how much one entity exceeds the other, is displaced into a lujvo place whose number is different for each lujvo. For example, while nelcymau has z4 as its fourth place, klamau has it as its seventh place. In any sentence where a difficulty arises, this amount-place can be redundantly tagged with vemau (for zmadu ) or veme'a (for mleca ) to help make the speaker's intention clear.

It is important to realize that such comparative lujvo do not presuppose their seltau. Just as in English, saying someone is younger than someone else doesn't imply that they're young in the first place: an octogenarian, after all, is still younger than a nonagenarian. Rather, the 80-year-old has a greater ni citno than the 90-year-old. Similarly, a 5-year-old is older than a 1-year-old, but is not considered “old” by most standards.

There are some comparative concepts in which the se zmadu is difficult to specify. Typically, these involve comparisons implicitly made with a former state of affairs, where stating a z2 place explicitly would be problematic.

In such cases, it is best not to use zmadu and leave the comparison hanging, but to use instead the gismu zenba , meaning “increase” (and jdika , meaning “decrease” , in place of mleca ). The gismu zenba was included in the language precisely in order to capture those notions of increase which zmadu can't quite cope with; in addition, we don't have to waste a place in lujvo or tanru on something that we'd never fill in with a value anyway. So we can translate “I'm stronger now” not as

which implies that I'm currently stronger than somebody else (the elided occupant of the second or z2 place), but as

Finally, lujvo with a tertau of traji are used to build superlatives. The place structure of traji is

Consider the gismu xamgu , whose place structure is:

The comparative form is xagmau , corresponding to English “better” , with a place structure (by the rules given above) of

We would expect the place structure of xagrai , the superlative form, to somehow mirror that, given that comparatives and superlatives are comparable concepts, resulting in:

The t2 place in traji , normally filled by a property abstraction, is replaced by the seltau places, and the t3 place specifying the extremum of traji (whether the most or the least, that is) is presumed by default to be “the most” .

But the set against which the t1 place of traji is compared is not the t2 place (which would make the place structure of traji fully parallel to that of zmadu ), but rather the t4 place. Nevertheless, by a special exception to the rules of place ordering, the t4 place of traji -based lujvo becomes the second place of the lujvo. Some examples: