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 y_3, if y_3 listens to a song, then y_3 is curious. For all y_3, if y_3 listens to a song, then y_3 is curious. For all y_3, if y_3 were curious, then y_3 is listening to a song. There is at least one y_3 for which y_3 is not curious.
There is at least one y_3 for which y_3 will not listen to a song can be inferred via the existential modus tollens rule. There is at least one y_3 for which y_3 will not listen to a song can be inferred via the existential modus tollens rule. For all y_3, y_3 will listen to a song if and only if y_3 is curious can be inferred via the universal biconditional introduction rule. For all y_3, y_3 will listen to a song if and only if y_3 is curious can be inferred via the universal biconditional introduction rule. For all y_3, y_3 is curious if and only if y_3 will listen to a song can be inferred via the universal biconditional introduction rule. For all y_3, y_3 is curious if and only if y_3 will listen to a song can be inferred via the universal biconditional introduction rule.