What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? Thomas is a bartender if and only if David is drinking water. Linda is writing a letter if and only if David is drinking water. Thomas is a bartender.
If Thomas were a bartender, then David is drinking water. If Linda writes a letter, then David is drinking water. If David drinks water, then Thomas is a bartender. If David drinks water, then Linda is writing a letter.