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: For all x_12, if x_12 were curious, then x_12 is poor. For all x_12, x_12 will write a letter or x_12 is curious. For all x_12, x_12 is a lawyer. For all x_12, x_12 will not work. For all x_12, x_12 will work if and only if x_12 will write a letter.
For all x_12, if x_12 works, then x_12 is writing a letter can be inferred via the universal biconditional elimination rule. For all x_12, if x_12 writes a letter, then x_12 is working can be inferred via the universal biconditional elimination rule. For all x_12, x_12 will not write a letter can be inferred via the universal biconditional elimination rule.