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: It is not snowing. Susan is an astronaut if and only if it is snowing. Sarah is sad or Susan is a bartender. Sarah is sad if and only if Susan is an astronaut.
If Susan were an astronaut, then it is snowing can be inferred via the biconditional elimination rule. If Sarah were sad, then Susan is an astronaut can be inferred via the biconditional elimination rule. If it snows, then Susan is an astronaut can be inferred via the biconditional elimination rule. If Susan were an astronaut, then Sarah is sad can be inferred via the biconditional elimination rule. Susan is not an astronaut can be inferred via the biconditional elimination rule.