For the “Nail Problem,” the applica

For the “Nail Problem,” the application of the first principle “separation in time” leads to conceptual solution of separation of conflicting requirements to the rod profile at the time of manufacturing process and at the time of nailing. So we can propose the next concept: during manufacturing of the nail it has a circular profile and during nailing the nail has a noncircular profile. How to implement this proposal? We can propose to make the standard nail a rod with a circular profile and then before hammering the nail, we flatten the profile with the hammer (see picture). Flat profile does not allow the nail to rotate