Why don't we use any articles before the countable noun "chairman" in the following sentence?
Potts was appointed chairman of the education committee.
Camera was invented by X.
I searched the Internet and came across some rules, but I wasn't able to put these particular ones into any categories.
And I know that we don't use any articles when we use possessive adjectives, e.g.
This is my book.
But again I didn't see this rule in the websites I surfed. I would appreciate it if you could link me to a good reference.