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: David is not a politician. John is curious if and only if Sarah is a server. David is a politician or John is reading a book. Sarah is a server.
John is reading a book can be inferred via the disjunctive syllogism rule. David is not a politician and Sarah is a server can be inferred via the conjunction rule. Sarah is a server and David is not a politician can be inferred via the conjunction rule. If John were curious, then Sarah is a server can be inferred via the biconditional elimination rule. If Sarah were a server, then John is curious can be inferred via the biconditional elimination rule.