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 Linda drives a car, then William is playing squash. If William plays squash, then Linda is a scientist. For all x_12, x_12 is a carpenter if and only if x_12 is a scientist.
If Linda drives a car, then Linda is a scientist can be inferred via the transitivity rule. For all x_12, if x_12 were a carpenter, then x_12 is a scientist can be inferred via the universal biconditional elimination rule. For all x_12, if x_12 were a scientist, then x_12 is a carpenter can be inferred via the universal biconditional elimination rule.