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: James is sleeping. Barbara is playing tennis if and only if Elisabeth is a writer. Sarah is an office clerk or it is snowing. Sarah is not an office clerk or Elisabeth is a writer. If it snows, then Barbara is playing tennis.
It is snowing or Elisabeth is a writer can be inferred via the resolution rule. If Barbara plays tennis, then Elisabeth is a writer can be inferred via the biconditional elimination rule. If Elisabeth were a writer, then Barbara is playing tennis can be inferred via the biconditional elimination rule.