In a message dated 12/1/2001 1:23:00 PM Central Standard Time, ragnarok@pobox.com writes:My question is, how do you do if-then-else constructions? Since "if P then Q, else R", assuming that Q and R are meant to be exclusive of one another, involves making all or none of P, Q, ~R true, Refgram says at 14.7 (342) that no combination of Lojban connectives can produce this without repeating at least one sentence. The most natural, then is (P iff Q) and (~P iff R): ga go P gi Q gi gonai P gi R. My memory (usual caveats) is that someone once proposed a single connective for this and that there is a way of dealing with it involving sets of statements, but I forget details on both. (If P and Q are not exclusive, the "iff" can be reduced to "only if" and there might be a simpler form -- there is a chart somewhere in some archive of what can and can't be done with three sentences and two connectives (plus various negations).) |