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_19, x_19 is a sailor if and only if x_19 is fast. For all x_19, x_19 will not play a game. There is at least one x_19 for which x_19 will sleep if and only if x_19 will play a game. For all x_19, x_19 is a sailor if and only if x_19 will sleep.
For all x_19, if x_19 were a sailor, then x_19 is fast can be inferred via the universal biconditional elimination rule. For all x_19, if x_19 were a sailor, then x_19 is sleeping can be inferred via the universal biconditional elimination rule. There is at least one x_19 for which if x_19 sleeps, then x_19 is playing a game can be inferred via the existential biconditional elimination rule. For all x_19, if x_19 were fast, then x_19 is a sailor can be inferred via the universal biconditional elimination rule. For all x_19, if x_19 sleeps, then x_19 is a sailor can be inferred via the universal biconditional elimination rule. There is at least one x_19 for which if x_19 plays a game, then x_19 is sleeping can be inferred via the existential biconditional elimination rule. There is at least one x_19 for which x_19 will not sleep can be inferred via the existential biconditional elimination rule.