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: Patricia is happy if and only if Mary is excited. Mary is not excited. Patricia is happy or Mary is not excited.
If Mary were excited, then Patricia is happy can be inferred via the rewriting rule. If Patricia were happy, then Mary is excited can be inferred via the biconditional elimination rule. If Mary were excited, then Patricia is happy can be inferred via the biconditional elimination rule. Patricia is not happy can be inferred via the biconditional elimination rule.