My question was more:
Does nga lu tawtute sì Na'vi mean nga lu tawtute ulte nga lu Na'vi, or something bizarre?
Yes. It totally does mean that.
No.
nga lu tawtute sì Na'vi = You are a skypeople and a Na'vi -> "mixture"
nga lu tawtute ulte nga lu Na'vi = You are a tawtute and you are a Na'vi. (It has also the meaning as one would sa to nga (1) you are a skypople and another nga (2) are a Na'vi)
The meaning is different.
I disagree. sì does not inherently have some meaning of making a mixture of the items given. After looking at every example made by Pawl, we see stuff like this:
Eo ayfo a fya’o lamu ayskxeta teya sì renulke.
‘The path ahead of them was full of rocks and irregular.’
Even some post titles like this one:
Tson sì Fpomron—Obligation and Mental Health
That is definitely not some freak hybrid mixture of obligation-and-mental health. It is a Noun array of size 2.
And here:
Pori fpomtokx sì fpomron yo’.
‘His physical and mental health are perfect.’
I have a doubt that this here is some hybrid mega-health made of both mental and physical. It's a list. We're iterating over a list of two things. To separate list items, we use sì...
And in this
comment:
Ngeyä ke ftang a tìkangkemìri sì tìkanuri sì fìlì’fyayä tìyawnìri seiyi oe irayo nìtxan.
~"I thank you very much for your nonstop work and intelligence and love for this language."
Tell me that's a mixture or hybrid. Clearly this is just an array of things, singular, non mutually-exclusive. We're just iterating one by one separating with sì. sì does not mean grinded up or genetic mixture.
So if I want to say "I am a Chinese person AND (I am) a Canadian person", can I say Oe lu ta Tsayna sì Kanada? That seems very wrong, as if "China and Canada" were the name of one country.
Is Oe lu ta Tsayna ulte (lu) ta Kanada correct without adding the lu?
Well, usually, nationalities use za'u ftu; Oe za'u ftu Tsayna sì Kanata.
The problem with this is not that there is some kind of impossible hybrid or mixture going on, but that you are trying to say you came from two very distant-from-each-other places at the same time. I'd love to know how you did that. Unless of course you came from China and Passed through Canada or came from Canada after passing through China. Or something like that. And as far as nationality goes, how can you honestly be both? You could probably be a citizen of both States, but can you actually claim to no longer be Chinese after having gained Canadian citizenship? Meh.
Anyways, this sentence is still technically grammatical, it just doesn't really make a lot of intuitive sense in any way semantically.
As for Na'vi: I think that this ambiguity that is part of natural languages. Why does Nga lu tawtute sì Na'vi not mean "You are a tawtute-and-Na'vi-at-the-same-time"? Well, because that meaning makes no sense
Over time, natural languages tend to evolve to remove confusing sentences with more than one meaning, so in general, although natural languages are horrible to describe logically, a normal person can usually find out what a sentence means without even thinking about it.
Absolutely this. ^
I studied mathematics, so my first reflex was to try to describe what I mean in terms of set theory, but I failed until now
I have some more ideas, if it works out, I'll post them here.
Set Theory is kinda wacky and unstable in certain situations. The barber paradox and all.

If the sentence would be like Menga lu tawtute sì Na'vi, it would be totally ok.
Right. And this would be correct too.
Menga = array("nga0", "nga1");
Mesute = array("tawtute", "N'vi");
Here, we are now mapping each element of the Menga array onto the Mesute array:
Menga[0] = Mesute[0];
Menga[1] = Mesute[1];
In poems, the sentence "Nga lu tawtute sì Na'vi" is ok. But usually, I would not write that as I ask me how one can be a (physical) tawtute and a (physical) Na'vi as one?
The words tawtute and Na'vi are a bad example to use because they are inherently mutuall exclusive unless you count Avatar as a special case of inheriting all attributes from both classes.
Let's use two things that are not mutually exclusive.
I am a man and student.
Oe lu tutan sì numeyu.
Is there a problem now?
Regarding Oe lu ta Tsayna sì Kanata, I think, this sentence is ok as ta shows that you are from China and Canada. Also, you can be "half Canadian and half Chinese" if one interprate it in this way and bot are humans.
Ok. I think I agree.
To make it totally clear that you are from the both country, I would write:
Oe lu ta Tsayna sì kop (ta) Kanata.
'I'm from China and also from Canada'
As for me, I could write:
Oe lu ta Europa sì Toitslan sì kop Romania.
I'm from Europe, Germany and also from Romania.
I'm not 100% sure if one can omit the second ta, but, I think, the context would make it clear. (maybe this thread could be interesting about that adposition in sentence)
I agree. Your usage of sì here checks out and makes sense.
As for
Oe lu ta Tsayna ulte (lu) ta Kanada
I believe, a version without the second lu is correct as Pawl used the same structure to omit lu and if the context is clear.
Hmmm... Something just feels off using ulte and there not being an explicit verb come after it. And once you've commited this redundant structure, why not just use the non-redundant structure using sì? It's more common and less clunky. But I guess saying Oe lu .. ulte oe lu.. ulte oe lu...... isn't incorrect, just redundant and weird.
I believe, a version without the second lu is correct as Pawl used the same structure to omit lu and if the context is clear.
Ah, I see. So it is fine to say Oe lu Atsankip nìNa'vi ulte Ačankif nìSahasì.
It got me thinking though. In the Canada/China example "sì" might work because you do have two different origins and are not completely from either. However, does that imply that Oe lu Atsankip nìNa'vi sì Ačankif nìSahasì is wrong?
Yes. Because I feel two different clauses here. I think it may be the different adverb after the ulte which seems to refer back to the first lu, making it more obvious that the "oe lu" has been repeated.
If you say ulte and after it there is no verb or no adverb that refers back to the verb in the first clause, It leaves me very inclined to ask you to finish your sentence with a verb or verb phrase. If you say sì, I expect to see a Noun array, Adjective array, or Noun-phrase array in the following forms:
A sì B; or
A sì B sì C......sì N; or
A, B, C..... sì N.
Oe lu Atsankip nìNa'vi ulte Ačankif nìSahasì.
I would say Oeru syaw fko Atsankip nìNa'vi sì (ulte?) Ačankif nìSahasì.
I feel it should be ulte, and I agree.
As I thought more about it, I think I did a little mistake about this:
As for Oe lu ta Tsayna ulte (lu) ta Kanada I believe, a version without the second lu is correct as Pawl used the same structure to omit lu and if the context is clear. |
Instead ulte, there should be sì. 
Oe lu ta Tsayna sì Kanata.
Oe lu ta Tsayna ulte kop oe lu ta Kanata.
^those.
If I look at Na'viteri, I can find this:
Plltxe fko san ngaru lu mowan Txilte ulte poru nga.
|
If one would split that sentence into two by removing ulte, the first part would make sense but not the second one:
[1] Plltxe fko san ngaru lu mowan Txilte
[2] poru nga
One can see that there is missing lu. It has been omitted, so it should be "lu poru nga" 'he/she has you' by context.
Right. ulte is around for the mere purpose to join two independent clauses. But of course, we know that sometimes things can be removed to make things smooth and less redundant. The whole sentence would have been something like this:
Plltxe fko san ngaru lu mowan Txlite ulte poru lu mowan nga sìk.
[
1] Plltxe fko san {
[
1a] ngaru lu mowan Txlte
ulte
[
1b] poru lu mowan nga
} sìk
Or this exaple:
Ayngari tengkrr ya wur sleru nì’ul, sìlpey oe, livu helku sang ulte te’lan lefpom.
|
The same here too,
[1] Ayngari tengkrr ya wur sleru nì’ul, sìlpey oe, livu helku sang
[2] ulte te’lan lefpom
Adding lu in the second part and it makes sense. (ok, in this case it works also as "te'lan lefpom - peaceful hearts" without lu)
Right again.
The whole redundant complete version:
Ayngari tengkrr ya wur sleru nì'ul, sìlpey oe tsnì livu helku sang ulte sìlpey oe tsnì livu te'lan lefpom.
Ayngari tengkrr ya wur sleru nì'ul
//Indepedent clause 1sìlpey oe {
//Independent clause 2; Unit A tsnì livu helku sang
//Dependent clause 1}
//end unit Aulte
//join Unit A with Unit Bsìlpey oe {
//Independent clause 3; Unit B tsnì livu te'lan lefpom
//Dependent clause 2}
//end unit BIt got me thinking though. In the Canada/China example "sì" might work because you do have two different origins and are not completely from either. However, does that imply that Oe lu Atsankip nìNa'vi sì Ačankif nìSahasì is wrong? |
Hmm, to be honest, I'm not sure as I still have to think if that sentence is listing words or not. My feel says that it's not a "list sentence", so there should be ulte.
I agree.
Oe lu Atsankip nìNa'vi ulte oe (kop) lu Ačankif nìSahasì.
I'm not sure if one can simply omit oe lu.
However, here is one without ulte:
Oe lu Atsankip nìNa'vi, släkop oe lu Ačankif nìSahasì.
I'd say the släkop feels nicer with a complementary ken'aw:
Oe lu ken'aw Atsankip nìNa'vi, släkop lu oe Ačankif nìSahasì.
Because for there to be a slä, there must be some statement you are saying something contrary or opposite to.
Oe lu Atsankip nìNa'vi ulte Ačankif nìSahasì. I would say Oeru syaw fko Atsankip nìNa'vi ulte Ačankif nìSahasì.
|
There should be sì.
"One calls me: X and Y and Z and..."
I only have the fear, that the adverbs there breaks the lists...
I would go for:
Oeru syaw fko Atsankip nìNa'vi fu Ačankif nìSahasì
Yes! I think that the adverb somehow break the list too. And I agree that you could also use fu there just as well. It nicely gets rid of the problem in this case.