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: Richard is playing squash if and only if it is snowing. For all x_10, x_10 will not listen to a song. Richard is playing squash if and only if Susan is listening to a song.
If Richard plays squash, then it is snowing can be inferred via the biconditional elimination rule. If Richard plays squash, then Susan is listening to a song can be inferred via the biconditional elimination rule. If it snows, then Richard is playing squash can be inferred via the biconditional elimination rule. If Susan listens to a song, then Richard is playing squash can be inferred via the biconditional elimination rule.