premise: Kyle has only visited Liberia, Alexander has only visited Zambia, Lester has only visited China, Nathaniel has only visited Burkina, Russell has only visited Belarus, Fred has only visited Côte D'ivore, Brett has only visited Kosovo, Lonnie has only visited Mauritius, Edwin has only visited Papua New Guinea, Derek has only visited São Tomé & Prícipe
hypothesis: Brett didn't visit Serbia