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 overcast, then Karen is cooking. If Sarah drinks water, then Karen is cooking. If Karen cooks, then it is overcast. It is overcast or Sarah is drinking water.
If Sarah drinks water, then it is overcast can be inferred via the transitivity rule. Karen is cooking can be inferred via the disjunction elimination rule. It is overcast if and only if Karen is cooking can be inferred via the biconditional introduction rule. Karen is cooking if and only if it is overcast can be inferred via the biconditional introduction rule.