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 it is sunny, then Patricia is writing a letter. Patricia is writing a letter if and only if Michael is running. It is sunny.
Patricia is writing a letter can be inferred via the modus ponens rule. If Patricia writes a letter, then Michael is running can be inferred via the biconditional elimination rule. If Michael goes running, then Patricia is writing a letter can be inferred via the biconditional elimination rule.