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: Elisabeth is not running. If it is sunny, then David is not working. It is cold if and only if Elisabeth is running. David is working.
It is not sunny can be inferred via the modus tollens rule. Elisabeth is not running and David is working can be inferred via the conjunction rule. David is working and Elisabeth is not running can be inferred via the conjunction rule. If it is cold, then Elisabeth is running can be inferred via the biconditional elimination rule. If Elisabeth goes running, then it is cold can be inferred via the biconditional elimination rule. It is not cold can be inferred via the biconditional elimination rule.