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: Charles is drinking water if and only if it is sunny. If James were poor, then Charles is drinking water. If Charles drinks water, then James is poor.
James is poor if and only if Charles is drinking water can be inferred via the biconditional introduction rule. Charles is drinking water if and only if James is poor can be inferred via the biconditional introduction rule. If Charles drinks water, then it is sunny can be inferred via the biconditional elimination rule. If it is sunny, then Charles is drinking water can be inferred via the biconditional elimination rule.