premise: Don has only visited San Mmarino, Clinton has only visited Sierra Leone, Alvin has only visited Argentina, Eric has only visited Ethiopia, Clifton has only visited Guinea-Bissau, Ramon has only visited Solomon Islands, Ken has only visited Barbados, Theodore has only visited Bangladesh, Tony has only visited Cambodia, Fred has only visited Republic of the Congo, Joel has only visited Algeria, Timothy has only visited Turkmenistan
hypothesis: Ken didn't visit Barbados