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: Patricia is reading a book if and only if it is snowing. If it is sunny, then it is snowing. If Patricia reads a book, then it is sunny.
If Patricia reads a book, then it is snowing can be inferred via the transitivity rule. If Patricia reads a book, then it is snowing can be inferred via the biconditional elimination rule. If it snows, then Patricia is reading a book can be inferred via the biconditional elimination rule.