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: Mary is playing a game. Elisabeth is fast if and only if Richard is running. Richard is running if and only if it is sunny. If Elisabeth were fast, then Mary is not playing a game.
Elisabeth is not fast can be inferred via the modus tollens rule. If Elisabeth were fast, then Richard is running can be inferred via the biconditional elimination rule. If Richard goes running, then it is sunny can be inferred via the biconditional elimination rule. If Richard goes running, then Elisabeth is fast can be inferred via the biconditional elimination rule. If it is sunny, then Richard is running can be inferred via the biconditional elimination rule.