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: Jennifer is sleeping if and only if Linda is writing a letter. For all x, if x plays tennis, then x is sleeping. For all x, if x sleeps, then x is playing tennis. For all x, x will not play tennis.
If Jennifer sleeps, then Linda is writing a letter can be inferred via the biconditional elimination rule. If Linda writes a letter, then Jennifer is sleeping can be inferred via the biconditional elimination rule. For all x, x will not sleep can be inferred via the universal modus tollens rule. For all x, x will play tennis if and only if x will sleep can be inferred via the universal biconditional introduction rule. For all x, x will sleep if and only if x will play tennis can be inferred via the universal biconditional introduction rule.