[Casiopea]

Shun:

....the Past Family are quite compatible with Present Perfect:

Ex: I have seen him in the past few days.

There's no argument there. Adverbs denoting unspecified time are compatible with the Present Perfect. (i.e., "in the past few days" denotes an unknown time within the past few days.)

• The present perfect is not compatible with adverbials denoting a specific past time.
  http://www-linguistics.stanford.edu/..._kiparsky.html
  
  We do NOT use specific time expressions with the Present Perfect. We cannot say, for example, "I have eaten spaghetti yesterday."
  http://conversa1.com/presentperfectpastsimple.htm
  
  You CANNOT use the Present Perfect with time expressions such as "yesterday," "one year ago," "last week," "when I was a chlid," "when I lived in Japan," "at that moment," "that day" or "one day."
  http://www.englishpage.com/verbpage/presentperfect.html