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_5, if x_5 plays squash, then x_5 is an electrician. For all x_5, if x_5 were sad, then x_5 is a nurse. For all x_5, x_5 will sleep or x_5 is sad. For all x_5, if x_5 were a nurse, then x_5 is an electrician. There is at least one x_5 for which if x_5 sleeps, then x_5 is playing squash.
For all x_5, if x_5 were sad, then x_5 is an electrician can be inferred via the universal transitivity rule. There is at least one x_5 for which if x_5 sleeps, then x_5 is an electrician can be inferred via the existential transitivity rule.