What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? If Mary were a janitor, then Patricia is a poet. If it rains, then Susan is an office clerk. For all y, y is not a poet. If Patricia were a poet, then Mary is a janitor. Susan is an office clerk if and only if Mary is a janitor.
If Susan were an office clerk, then Mary is a janitor. If Mary were a janitor, then Susan is an office clerk.