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 Michael drinks water, then Robert is reading a book. If Barbara were a mechanic, then Michael is drinking water. If Michael drinks water, then Barbara is a mechanic. If Robert reads a book, then it is not overcast. It is overcast and it is cloudy.
If Michael drinks water, then it is not overcast can be inferred via the transitivity rule. If Barbara were a mechanic, then Robert is reading a book can be inferred via the transitivity rule. It is overcast can be inferred via the simplification rule. It is cloudy can be inferred via the simplification rule. Barbara is a mechanic if and only if Michael is drinking water can be inferred via the biconditional introduction rule. Michael is drinking water if and only if Barbara is a mechanic can be inferred via the biconditional introduction rule.