What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? For all x_12, x_12 is sad if and only if x_12 is a police officer. There is at least one x_12 for which if x_12 writes a letter, then x_12 is a lawyer. For all x_12, x_12 is sad or x_12 will write a letter. For all x_12, x_12 is a lawyer if and only if x_12 is a police officer.
For all x_12, if x_12 were sad, then x_12 is a police officer. For all x_12, if x_12 were a lawyer, then x_12 is a police officer. For all x_12, if x_12 were a police officer, then x_12 is sad. For all x_12, if x_12 were a police officer, then x_12 is a lawyer.