I suspect dialectal variation is involved concerning whether “has Vpp” is used properly with “since” in relation to durative and punctual predicates in the following. Note also that dialectal variation is not restricted to AmE/BrE difference; it could also involve internal differences within AmE or BrE.
It is over 20 years since John has died for his country.
It is over 20 years since John has lived in this country.
I’ve seen the following sentence in Practical English by Michael Swan:
I’ve known her since I’ve lived in this street.
If you reject the first two sentences, do you reject the third one?
If not, could you explain the difference?
Previous threads do not deal with the variation in acceptability of present perfect in since-clauses.
“Since”, in this context, means from a particular time in the past until a later time. A ‘particular’ time would be a fixed event that began the time period, not the period itself.
We only say someone ‘has died’ when referring to their current status (ie they are dead). The fixed event is when they died, or their death. So, in your first example, you need to remove the word ‘has’ for it to make sense.
“Living” in this country is not a fixed event, so in the second example, you need to refer to his beginning to live here.
It is over 20 years since John died for his country.
It is over 20 years since John began living in this country.