Well i think it just depends on how 'significant' you need the phd to be. As an example of what I mean, consider the first issue of this years Annals of mathem

Well i think it just depends on how 'significant' you need the phd to be. As an example of what I mean, consider the first issue of this years Annals of mathematics [1] and note that there is not a single grad student on any of the papers, first author or otherwise. [1] http://annals.math.princeton.edu/2018/188-1 http://annals.math.princeton.edu/2018/188-1