Premise: There ought to be room in the retelling of it for the letters Mark Twain and Frederick Douglass exchanged, for the similarities between Invisible Man and Ben Franklin's Autobiography , for the presence of Charles Chesnutt at the banquet to honor Twain shortly before the latter's death, and for the monument in Mississippi to the slaves who rode with a band of Confederate irregulars.

Hypothesis: Mark Twain and Frederick  Douglas exchanged letters.
Relation: entailment