Is this sentence correct?
- Although I would like to start, nevertheless it is not possible.
Or should it be:
- Although I would like to start, it is not possible.
- I would like to start, nevertheless it is not possible.
Is this sentence correct?
- Although I would like to start, nevertheless it is not possible.
Or should it be:
- Although I would like to start, it is not possible.
- I would like to start, nevertheless it is not possible.
Your example #1 is fine.
Consider this example from the 2002 CGEL, page 776, example [2.iii ], which is structured very similar to your example:
[2.iii ] Although he affects a gruff exterior in many instances, nevertheless he is fundamentally a man of warm heart and gentle disposition.
and their explanation:
Another very common case is represented in [2.iii ], where the connective adjunct has a reduplicative role: the relation between the main and subordinate clauses is already marked by although, so that nevertheless simply marks this relationship a second time.
ASIDE: As to your other two examples, example #2 is fine; but example #3 might be a bit controversial in that some people might see it as being a comma splice, and so they might expect or demand a semicolon or period or em dash to be used instead of a comma. Example #3 is okay to me for informal style, but if I'm writing in a very formal style or for a formal register then I might think twice before using a comma there like that.
NOTE: The 2002 CGEL is the 2002 reference grammar by Huddleston and Pullum (et al.), The Cambridge Grammar of the English Language.
#Although I would like to start, nevertheless it is not possible. (not good)
The problem with the Original Poster's sentence is not the use of although and nevertheless in the same sentence. It is perfectly grammatical to do this:
Notice that in the example above nevertheless comes in between the subject he and the verb agreed. If we put it before the subject the sentence will not be good:
The Original Poster's example can be made good, if we move the adverb to the same position:
The Original Poster's second examples are both good:
Although I would like to start, it is not possible.
I would like to start. Nevertheless, it's not possible.
Notice, though, that in the second example, it is better to use a full stop, not a comma to separate the two sentences.
The two are not normally used in the same sentence.
Judges may not wish to mete out life-sentences for non-violent drug-related crimes; nevertheless, under current US law they must.
Although judges may not wish to mete out life-sentences for non-violent drug-related crimes, under current US law they must.
Short answer: Your first sentence isn't correct at all. You can use either of the conjunctive adverbs to connect the two clauses, but they shouldn't be there together. Also, some believe it's better to use a semicolon to connect two complete sentences.
Long answer: Nevertheless is a conjunctive adverb:
A conjunctive adverb is an adverb that connects two independent clauses. Conjunctive adverbs show cause and effect, sequence, contrast, comparison, or other relationships. (Emphasis mine)
This option is at times considered correct if seen by some speakers:
I would like to start, nevertheless, it is not possible.
About although, it's categorized as a subordinate conjunction. So this is correct also:
Although I would like to start, it is not possible.
Note that connecting the two sentences using both nevertheless and although isn't correct as both are some kinda "conjunctions"!
But wait...
This is rather pedantic, but some people (including the author of this tutorial) believe that if you are to connect two whole sentences, a semicolon is preferred over a comma.
So, the fully correct sentence with nevertheless is:
I would like to start ; nevertheless, it is not possible. I would like to start. Nevertheless, it is not possible.