Subject: Predicate logic and childhood.

From: Robin Lee Powell <[email-masked]>
Date: Mon, 30 Apr 2001 11:45:21 -0700

So, having thought about this more, and remembering that the connectives
in lojban are based on predicate logic, and that I know how to do that,
here's some more on logical connective usage.

Take the sentence:

ko ca gasnu le nu le do kumfa ku cnici

Call that sentence C. C is true iff, at a time that is more-or-less
'now', the child in the agentive cause of eir room becoming tidy.

Next, we have:

mi ba curmi le nu do klama le panka

Call that sentence P. P is true iff, at a time that is more-or-less in
the future, the parent gives the child permission to go to the park. I
take it as obvious that P implies that such permission is not currently
given (or there would be no ba tag).

Take:

C .inaja P

Or, alternatively:

If C then P

using standard predicate logic meaning of 'If ... then ...'.

Then we have the standard 4 cases:

The child cleans eir room. Afterwards, the parent gives the child
permission to go to the park. Clearly, with P and C both true, C -> P
is true.

The child cleans eir room. Afterwards, the parent does not give the
child permission to go to the park. C -> P is false, ergo the parent
lied (stated a false predication; what else could lying be in a logical
language?).

The child does not clean eir room. C is false, C -> P is therefore
always true. This is actually really useful, because at this point
_anything_ follows, including the parent giving the child a whuppin'.
8)

However, for maximum clarity it would perhaps be best to use

C .ijo P

so that if the child does not clean eir room, and the parent allows the
child to go to the park, the parent has lied again. Which the parent
will probably reluctant to do, so this helps constrain the parent to not
change eir mind.

-Robin

-- 
http://www.digitalkingdom.org/~rlpowell/ BTW, I'm male, honest.
le datni cu djica le nu zifre .iku'i .oi le so'e datni cu to'e te pilno
je xlali -- RLP http://www.lojban.org/