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, x_12 will climb a mountain if and only if x_12 is a police officer. Jessica is playing tennis or Richard is not climbing a mountain. Mary is writing a letter if and only if Jessica is playing tennis. Mary is not writing a letter.
If Richard climbs a mountain, then Jessica is playing tennis can be inferred via the rewriting rule. If Mary writes a letter, then Jessica is playing tennis can be inferred via the biconditional elimination rule. If Jessica plays tennis, then Mary is writing a letter can be inferred via the biconditional elimination rule. Jessica is not playing tennis can be inferred via the biconditional elimination rule. For all x_12, if x_12 climbs a mountain, then x_12 is a police officer can be inferred via the universal biconditional elimination rule. For all x_12, if x_12 were a police officer, then x_12 is climbing a mountain can be inferred via the universal biconditional elimination rule.