Instruction level parallelism
Operation 3 depends on the results of "e" and "f" which are calculated from operations 1 and 2, so "g" cannot be calculated until both of "e" and "f" are computed.  However, operations 1 and 2 do not depend on any other operation, so they can be computed simultaneously.  If we assume that each operation can be completed in one unit of time then these three instructions can be completed in a total of two units of time, giving an ILP factor of 3/2; which means 3/2 = 1.5 greater than without ILP.