|Lojban For Beginners — velcli befi la lojban. bei loi co'a cilre|
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How can you tell someone is a computer programmer?
You ask them "Do you want milk or sugar?", and they answer "Yes."
In natural languages, that kind of answer is liable to get you a clip around the ears. That is because natural languages are run not only by logic, but also by social conventions. And one of the most important social conventions about language (Gricean informativeness, for those taking third year linguistics courses) is that, whatever you say, you should say enough to fully inform your listener about what's going on. If I ask "Do you want milk or sugar?", I need that information in order to prepare you a cup of coffee to your liking. Answering me "yes" doesn't give me much to go on.
As far as strict logic is concerned, though, "Yes" is the only proper answer, as computer programmers (and logicians, and Lojbanists) discover much to their amusement — and to the irritation of the rest of the world. That is because the question is phrased as a yes/no question; and OR, in the question, does not behave any differently as a logical connective than AND. ("Yes" is an appropriate answer to "Do you want milk and sugar?" Of course, now it's "No" which is not helpful as an answer.)
The same holds for Lojban, of course: .i xu do djica lenu jmina loi ladru .a loi sakta is a yes/no-question, and the only proper answers are .i go'i and .i na go'i. What you should actually be asking, if you want to be logically correct, is "Identify which of the following you want: milk, sugar."
You could say that, but it's not much like Lojban's fill-in-the-slot approach. Instead, Lojban sneakily asks you to fill in a slot you might not have expected: not the 'milk' slot, or the 'sugar' slot, but the connective slot:
By filling in the slot, you get to pick what you want. If you say .e, you are saying the sentence .i do djica lenu jmina loi ladru .e loi sakta — in other words, you want both. If you say .enai, you are using the AND NOT connective, which negates what follows it: so you are saying "I want milk, and not sugar." If you want to negate what went before the connective instead, you use na.e. (You can negate what goes before any connective by putting na in front of it.) So if you answer na.e, you are saying "I want not milk, and sugar" (or, as is more usual in English, "not milk, but sugar") — which means that you are picking only sugar. If you want neither, you can negate both sides: na.enai. You can still be unhelpful with your response: .a would leave us right where we started, for instance. But at least this way you have a logically consistent way of picking alternatives presented to you.
.i do djica lenu jmina loi ladru ji loi sakta
You want to add milk ___ sugar.
Tip: Be careful, though: this kind of question doesn't really generalise past two alternatives, so you may still have to fall back on the 'pick zero or more alternatives out of the following' approach.
You can ask questions in the same way about the other kinds of connectives we have looked at. The connective interrogative for tanru is je'i, and the connective interrogative for bridi-tails is gi'i.
x1 is a hospital treating patient(s) x2 for condition/injuries/disease/illness x3
x1 remains/stays at/abides/lasts with x2
x1 studies/is a student of x2; x1 is a scholar; (adjective:) x1 is scholarly
Answer these questions in Lojban.