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: For all x_10, x_10 is a scientist or x_10 is an office clerk. For all x_10, x_10 will not write a letter. For all x_10, x_10 will go running. For all x_10, x_10 will write a letter if and only if x_10 is a scientist.
For all x_10, if x_10 writes a letter, then x_10 is a scientist can be inferred via the universal biconditional elimination rule. For all x_10, if x_10 were a scientist, then x_10 is writing a letter can be inferred via the universal biconditional elimination rule. For all x_10, x_10 is not a scientist can be inferred via the universal biconditional elimination rule.