This is a follow-up to the thread 'How to do "but/however"'.

It doesn't seem that there are better terms than the ones in the
subject-line, so no term that covers all three. "But" is a conjunction,
"however" is a conjunctive adverb and "although" is a subordinator
though i prefer the Norwegian term, which Anglified would read
_subjunction_. Maybe we could then call the conjunctive adverbs
"adjunctions" and the entire grep "junctions" :), patterning like
proclitic, enclitic, clitic.

In addition, English and many other languages have sentential/clausal
adverbs separate from the conjunctive adverbs, which modify the entire
sentence/clause without connecting them in any way with another

As the finnish mutta/vaan-examples show (both used for sentential but),
the set of these "junctions" aren't the same between languages.
Norwegian for instance has the conjunctions og (and) eller (or) men
(but) and for (because), and no more.

A handy tool for conlanging would be the minimum set of necessary
junctions, or junction-meanings, this would probably be quickly achieved
if we collaborated on a list. So, in this mail I'll look at one
subset of them, junctions marking condition.

Conditional markers: 
    if, unless, only if, whether or not, even if, in case (that)

Can these be collapsed? Lets see:
    if X, then Y / Y if X
    Y unless X = Y if not X

"Unless" seems to be a negated "if".

    Y in case of/that X

Clearly an "if".

    X whether or not Y / X whether Y or not

This is a strange one, choosing between two alternatives, Y or not-Y.
More like an "or" than an "if". Taruven marks the verb of the Y in this
case (beware of UTF-8 and monospace font!): 

    ksyahr   qaro         sav žariseðaþ
    ksyahr   qa  -ro      sav žaris  -eð  -aþ
    consider eat -whether my  supper -GEN -OBJECT
    "I consider whether I will eat my supper (or not)"

That leaves "only if" and "even if". "Only if" is often written "iff" in
maths- and logic-texts. It differs from ordinary "if" in that the Y of
"Y iff X" can only happen if the X is true, meaning that if Y is true, X
must be true, or you can think of it as an if that goes both ways: if X
then Y AND if Y then X. With an ordinary "if", if Y is true we can't be
absolutely sure that the X is also true, the if is one way only. Handy
distinction to have, that, and maybe suitable for a conjunction. 

"Even if" seems similar to but/however in that it says that something is
unexpected, surprising, so I'd do as with the "but", use a
mirative-marker and a regular "if".

Ergo, we can manage with only "if, iff, whether", maybe even only "if".

How many of these does a pidgin or creole have, and what does your
conlangs and natlangs do?