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 for which if y were sad, then y is reading a book. For all y, y is a carpenter if and only if y is a mechanic. For all y, y will read a book if and only if y is a carpenter. For all y, y is not a mechanic.
For all y, if y were a carpenter, then y is a mechanic can be inferred via the universal biconditional elimination rule. For all y, if y reads a book, then y is a carpenter can be inferred via the universal biconditional elimination rule. For all y, if y were a mechanic, then y is a carpenter can be inferred via the universal biconditional elimination rule. For all y, if y were a carpenter, then y is reading a book can be inferred via the universal biconditional elimination rule. For all y, y is not a carpenter can be inferred via the universal biconditional elimination rule.