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: Thomas is reading a book if and only if it is overcast. For all z_1, z_1 will read a book.
If Thomas reads a book, then it is overcast can be inferred via the biconditional elimination rule. If it is overcast, then Thomas is reading a book can be inferred via the biconditional elimination rule.