Question: Who is the paternal grandfather of Ferdinand, Duke Of Viseu?
Sentence (from "Edward, King of Portugal"): Duarte (31 October 1391 – 9 September 1438), known in English as Edward and called the Philosopher ("o Rei-Filósofo") or the Eloquent ("o Eloquente"), was King of Portugal from 1433 until his death.
Relevant evidence: No