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: If Linda plays squash, then Patricia is writing a letter. Karen is drinking water if and only if Patricia is writing a letter. If it snows, then Patricia is not writing a letter. Linda is playing squash or Karen is drinking water.
If Karen drinks water, then Patricia is writing a letter can be inferred via the biconditional elimination rule. If Patricia writes a letter, then Karen is drinking water can be inferred via the biconditional elimination rule.