As any 10-year-old knows (and game theorists can now elaborately prove), three-person secrets are particularly troublesome in this regard, because nobody can ever pinpoint which of the other two might have cheated.
A common exercise among game theorists is attempting to brainstorm methods of pinpointing which of the other two might have cheated. 
mnli hypothesis: A common exercise among game theorists is attempting to brainstorm methods of pinpointing which of the other two might have cheated.  premise: As any 10-year-old knows (and game theorists can now elaborately prove), three-person secrets are particularly troublesome in this regard, because nobody can ever pinpoint which of the other two might have cheated.