Subject: Re: [lojban] Logic course

From: [email-masked]
Date: Tue, 19 Mar 2002 12:24:55 EST

In a message dated 3/19/2002 9:52:05 AM Central Standard Time, 
[email-masked] writes:

> 1){roda de zo'u li da su'i de du li no}
> (can only da de and di (w/ subscripts) be used as bound variables ?) what
> does
> 1'){roxy. zy. zo'u li xy su'i zy. du li no} mean ? the same as 1)?
> 

Apparently only {da, de, di} . {xy} and so on are anaphoric pronouns and 
will pick up other things. BUT in a clearly MEX environment, they function 
as variables, for reading formulae. Question: How tell that this is a 
clearly MEX environment. I think it is, since there is a formula to read: <
1)AxEy(x + y = 0)>

Further, the parser (do check this always) rejects {li da} out of hand, so 
use either just {da}, etc. throughout or {li xy}

<how long do bound variables last, if propositions are logically connected ?>

Disputable, but the reasonable answer is: to the end of the scope of its 
binding. In non-formulaic Lojban we fudge a bit after that.

<2)AxAyAz(x + y = x + z = 0 => y = z)
2){roda rode rodi zo'u du li da su'i de li da su'i di li no .inaja du li de
li di} this can also be written
2') {roda su'epada zo'u du li da su'i de li no}, but we are just starting
and are not working with languages as powerfull as lojban yet .uinai>

Same problem with {li da} as before. I think you need {fa} in front of the 
right-shifted first arguments: {roda rode rodi zo'u du fa da su'i de da su'i 
di li no .inaja du fa de
di} This still does not work: {du} is a two-place argument, so the three 
place version does not work; you need {roda rode rodi zo'u du fa da su'i de 
da su'i di ije du fa da su'i di li no .inaja du fa de di}
And finally, the parser does not see {da su'i de} etc. as sumti, but takes 
the {da} and puzzles about the rest. I wonder if it goes better with {xy}, 
etc.

{su'epa de} and I think the default on {su'e} is {pa}, so just {su'e de}. 

<3)Ey(x = y * y)
3){da zo'u li xy. du li da pi'i da}>

Still doesn't get {pi'i da} nor {li da}. I expect that this is true (mut 
mut) for 4 as well.
And 5. 
<5)Ax(Ez(x = z**2) => Ey(x = y * 4))
5){roda zo'u de zo'u li da du li de te'a re .inaja di zo'u li da du li di
pi'i vo}>

An argument for forethought connectives, though I think this works out right. 
And you could skip the internal preneces. But, perversely, {vo} needs a 
{li}.

I think part of the problem is the mixture of MEX, which is for reading a 
formula, with ordinary Lojban, which is about saying what the formula means. 
They do not mix well. I suspect that all the {su'i} etc. expressions need a 
descriptor in ordinary Lojban, something like {me'o}: {li xy du me'o da pi'i 
da} seems to work somewhat better (it still fails, but I am begining to 
suspect that the parser doesn't do MEX any better than we do).