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: For all x_14, x_14 will not play a game. Thomas is taking a plane if and only if Robert is playing a game. If Thomas doesn't take a plane, then it is sunny.
If Thomas takes a plane, then Robert is playing a game can be inferred via the biconditional elimination rule. If Robert plays a game, then Thomas is taking a plane can be inferred via the biconditional elimination rule.