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: If Jessica were happy, then John is rich. If John were rich, then Jessica is happy. John is rich or Jessica is not happy.
If Jessica were happy, then John is rich can be inferred via the rewriting rule. Jessica is happy if and only if John is rich can be inferred via the biconditional introduction rule. John is rich if and only if Jessica is happy can be inferred via the biconditional introduction rule.