I recently learnt that だれも means "everyone" with an affirmative verb and "no-one" with a negative verb. So, the literal translation of the Japanese "No-one is here" would be "Everyone is not here". Then how would one go about saying "Not everyone is here?"
`Not everyone is here.' is translated into
Here 「すべて～ではない」is a partial negation.
`Everyne is not here' is translated into
Here「すべて～ない」is a total negation.
If you are familiar with formal language representations :-),
We can interpret the above situation as below:
When P(x)≡[x is here],
Not everyone is here.
⇔ No one is here.
⇔ Everyone is not here.
In contract to the expresson 「すべての人がここにいない」(total negation),
the expression 「すべての人はここにいない」is somewhat ambiguous.
this can be interpreted as both partial negation and total negation.
"Not everything is X" is the same logically as "Some things (exist which) are not X", so in the general case you can do something like
there also exist things that are not blue
= some of them aren't blue
= not every one of them is blue
Unfortunately, for the "is here" case, where our verb is いる, that would give us something like いない人もいる, which is at best confusing, so we might want to look for a rephrase.
来ていない人もいる there are people who haven't come / not everyone is here
全員そろっていない the group of everyone is not fully gathered
Depending on how you want the emphasis you can also negate the clause "everything is X" directly by inserting a noun like わけ:
it is not that everyone is here