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: Joseph is a server if and only if Barbara is a lawyer. Joseph is not a server. If Jennifer were not a poet, then Robert is a mechanic. Barbara is a lawyer if and only if Jennifer is a poet.
If Joseph were a server, then Barbara is a lawyer can be inferred via the biconditional elimination rule. If Barbara were a lawyer, then Jennifer is a poet can be inferred via the biconditional elimination rule. If Barbara were a lawyer, then Joseph is a server can be inferred via the biconditional elimination rule. If Jennifer were a poet, then Barbara is a lawyer can be inferred via the biconditional elimination rule. Barbara is not a lawyer can be inferred via the biconditional elimination rule.