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: It is cold if and only if Joseph is a writer. It is cold if and only if Susan is poor. If Joseph were a writer, then Susan is poor.
If it is cold, then Joseph is a writer can be inferred via the biconditional elimination rule. If it is cold, then Susan is poor can be inferred via the biconditional elimination rule. If Joseph were a writer, then it is cold can be inferred via the biconditional elimination rule. If Susan were poor, then it is cold can be inferred via the biconditional elimination rule.