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: There is at least one x_6 for which if x_6 were poor, then x_6 is a sailor. For all x_6, if x_6 were a sailor, then x_6 is poor. For all x_6, x_6 is not a writer. For all x_6, x_6 is poor if and only if x_6 is a writer.
There is at least one x_6 for which x_6 is poor if and only if x_6 is a sailor can be inferred via the existential biconditional introduction rule. There is at least one x_6 for which x_6 is a sailor if and only if x_6 is poor can be inferred via the existential biconditional introduction rule. For all x_6, if x_6 were poor, then x_6 is a writer can be inferred via the universal biconditional elimination rule. For all x_6, if x_6 were a writer, then x_6 is poor can be inferred via the universal biconditional elimination rule. For all x_6, x_6 is not poor can be inferred via the universal biconditional elimination rule.