Subject: Re: [lojban] A or B, depending on C, and related issues

From: [email-masked]
Date: Thu, 9 Aug 2001 20:42:51 EDT

In a message dated 8/9/2001 6:24:35 PM Central Daylight Time, 
[email-masked] writes:

> "if P then Q, else R," which are also pleasantly simple:
> >(if P then Q) and (if not P then R)" and "(P iff Q) and (not P iff R)" 
> >While
> >I am sure there are easier ways to show that these are the simplest forms 
> >for
> >these functions, I confess to just having run all the possibilities from
> >disjunctive normal forms on down.
> 
> Neither of them is "Q or R, depending on P" though. One of
> the versions of that would be:
> 
> [(if P then Q) and (if not P then R)] xor
> [(if not P then Q) and (if P then R)]
> 

Well, they are in fact the two things that I usually see when I ask for an 
explanation of that phrase, and they do fit the requirements. I admit the 
other is more thorough sounding, but does it really introduce a new 
possibility in the concrete? Similarly, is the "P or Q, depending on the 
weather" more than an inspecific way to saying something of the first or 
second sort -- just failing to mention how the dependency goes. Since this 
all is out of the {makau} thread, which is about hiding significant 
information, perhaps that is an important fact, but then we need to see how 
these connections are going to work: (if Pkau then Q) and (if not-Pkau then 
R)?

The best simplification I could find in a dash was ~(Q&R) &(P => QvR) , 
which, while shorter, is markedly less informative when talking about 
depndencies.