Are both the same?
All efforts have turned up nothing yet.
All efforts have resulted in nothing so far.And this;
All efforts have failed so far.

Question

Are both the same?
All efforts have turned up nothing yet.
All efforts have resulted in nothing so far.And this;
All efforts have failed so far.

Answer

The sentences are the same. You can even create more patterns with the help of
'up to now',
 till now
hitherto
still (instead of 'so far' and 'yet')

Answer

They both mean the same thing to me, but I think that:
- the first one is informal 
- the second is more formal

Answer

pretty much the same...