Question: Who reigned for 50 months as lineal champion  and fought Richard Williams?
Sentence (from "Lineal championship"): However, there is no single canonical list of lineal champions at any weight class, because there is no agreed upon method of determining the starting point for each lineage and conflicting opinions on what to do when the current champion retires or moves to a different weight class, although there is agreement that any stripping of a title be discounted.
Relevant evidence: No