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You write a PhD thesis, in the acknowledgments you thank a series of people from collaborators, to friends, to peers, to professors. Many of these people will never read the thesis so what is the point to acknowledge them? It seems more an exercise for myself. This is different than the acknowledgments in a paper because PhD acknowledgments tend to be more personal and might include friends or people with a non-working relationship that helped in a way that it is not strictly related to the thesis.
Should I send them a copy of the thesis AND mention that I have acknowledged them, or simply let them know in some informal way that I acknowledged them, maybe next time I meet them or sending them a quick email?
It seems a pointless message if they don't know they have been thanked.