, , or ), and are the set of natural variables for that potential, excluding . If we use all thermodynamic potentials, then we will have more equations of state such as

and so on. In all, if the thermodynamic space is dimensions, then there will be equations for each potential, resulting in a total of equations of state because thermodynamic potentials exist. If the equations of state for a particular potential are known, then the fundamental equation for that potential (i.e., the exact differential