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 Jessica doesn't drink water, then it is overcast. Charles is sad if and only if Jessica is drinking water. Charles is not sad. It is overcast or Joseph is not a politician.
If Joseph were a politician, then it is overcast can be inferred via the rewriting rule. If Charles were sad, then Jessica is drinking water can be inferred via the biconditional elimination rule. If Jessica drinks water, then Charles is sad can be inferred via the biconditional elimination rule. Jessica is not drinking water can be inferred via the biconditional elimination rule.