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: Jessica is reading a book or Joseph is an astronaut. Jessica is not reading a book. If it is cold, then Joseph is an astronaut. If Joseph were an astronaut, then it is cold.
Joseph is an astronaut can be inferred via the disjunctive syllogism rule. It is cold if and only if Joseph is an astronaut can be inferred via the biconditional introduction rule. Joseph is an astronaut if and only if it is cold can be inferred via the biconditional introduction rule.