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 David climbs a mountain, then Richard is playing squash. If Mary works, then it is cloudy. If David plays a game, then David is climbing a mountain. If Richard plays squash, then Mary is working. If Robert were a lawyer, then David is playing a game.
If David climbs a mountain, then Mary is working can be inferred via the transitivity rule. If David plays a game, then Richard is playing squash can be inferred via the transitivity rule. If Richard plays squash, then it is cloudy can be inferred via the transitivity rule. If Robert were a lawyer, then David is climbing a mountain can be inferred via the transitivity rule.