I think you misunderstand the purpose of a summary of a person . It isn't P(think of this subject | think of this person), it's P(think of this person | think of this subject).
Likewise, in a summary of a subject, a person would show up if P(think of this subject | think of this person) shows up.
So, for instance, Nelson Mandela shows up in the intro to Apartheid and vice versa; Pi shows up in Fabrice Bellard, but Bellard doesn't show up in Pi; Poor Richard's Almanack links to Benjamin Franklin but Benjamin Franklin doesn't mention PRA in its summary.
Likewise, in a summary of a subject, a person would show up if P(think of this subject | think of this person) shows up.
So, for instance, Nelson Mandela shows up in the intro to Apartheid and vice versa; Pi shows up in Fabrice Bellard, but Bellard doesn't show up in Pi; Poor Richard's Almanack links to Benjamin Franklin but Benjamin Franklin doesn't mention PRA in its summary.