Re-discussing the Reality on Theory of Value by Marx and Engels by Methodology

Marx and Engels have the same concept that is a rule of utility and labor cost. Value has the same meaning as productive force. But such theory of value appears in Capital is from abstraction to concretion or from the theory of labor value to concretion. We may find that every step to concretion is finished by both the theory of labor value and the theory of utility value. Their theory depends on the system of historical materialism. Clearly, this theory is not limited to the theory of labor value and it is a system of the theory of utility/labor value.