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, x will go running if and only if x is sad. There is at least one x for which x will go running or x is not sad.
There is at least one x for which if x were sad, then x is running can be inferred via the existential rewriting rule. For all x, if x goes running, then x is sad can be inferred via the universal biconditional elimination rule. For all x, if x were sad, then x is running can be inferred via the universal biconditional elimination rule.