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 Joseph were a nurse, then James is not working. If Elisabeth makes tea, then it is snowing. If Susan were a scientist, then James is working. Susan is a scientist or Elisabeth is making tea. If it snows, then James is working. If James works, then it is snowing.
If Elisabeth makes tea, then James is working can be inferred via the transitivity rule. If Susan were a scientist, then it is snowing can be inferred via the transitivity rule. It is snowing if and only if James is working can be inferred via the biconditional introduction rule. James is working if and only if it is snowing can be inferred via the biconditional introduction rule.