What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? Name the inference rule being used: If William sleeps, then it is sunny. Linda is a server or William is not sleeping. If it is sunny, then William is sleeping.
If William sleeps, then Linda is a server can be inferred via the rewriting rule. William is sleeping if and only if it is sunny can be inferred via the biconditional introduction rule. It is sunny if and only if William is sleeping can be inferred via the biconditional introduction rule.