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, if y makes tea, then y is reading a book. For all y, y will climb a mountain if and only if y will read a book. For all y, y will not make tea. For all y, if y reads a book, then y is making tea.
For all y, y will not read a book can be inferred via the universal modus tollens rule. For all y, y will make tea if and only if y will read a book can be inferred via the universal biconditional introduction rule. For all y, y will read a book if and only if y will make tea can be inferred via the universal biconditional introduction rule. For all y, if y climbs a mountain, then y is reading a book can be inferred via the universal biconditional elimination rule. For all y, if y reads a book, then y is climbing a mountain can be inferred via the universal biconditional elimination rule.