premise: Francisco has only visited Croatia, Gregory has only visited Antigua & Barbuda, Reginald has only visited Guinea, George has only visited Belize, Kurt has only visited Cabo, Randall has only visited Dominica, Roger has only visited Bahrain, Nicholas has only visited Vietnam, Duane has only visited Mali, Allan has only visited Republic of the Congo, Lewis has only visited Burundi
hypothesis: Duane didn't visit Mali