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 x for which if x were fast, then x is reading a book. For all x, if x reads a book, then x is fast. For all x, if x were fast, then x is reading a book.
For all x, x will read a book if and only if x is fast can be inferred via the universal biconditional introduction rule. For all x, x is fast if and only if x will read a book can be inferred via the universal biconditional introduction rule. There is at least one x for which x is fast if and only if x will read a book can be inferred via the existential biconditional introduction rule. There is at least one x for which x will read a book if and only if x is fast can be inferred via the existential biconditional introduction rule.