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: There is at least one y_2 for which if y_2 were sad, then y_2 is a poet. For all y_2, y_2 will read a book if and only if y_2 will play squash. For all y_2, if y_2 reads a book, then y_2 is sad.
There is at least one y_2 for which if y_2 reads a book, then y_2 is a poet can be inferred via the existential transitivity rule. For all y_2, if y_2 reads a book, then y_2 is playing squash can be inferred via the universal biconditional elimination rule. For all y_2, if y_2 plays squash, then y_2 is reading a book can be inferred via the universal biconditional elimination rule.