What are the other assumptions? The hull condition, hull assumption in thin ship theory, we said that any breadth dimension of the ship is small compared to the length dimension that is, ship is thin, b is small compared to l everywhere on the ship, or slender, slender said that both breadth and draft are small compared to length. These give very nice mathematical formulations either of these theories, but different, so, I will not go details into of this. The other assumptions are the wave height is small, waves generated, the height of those waves is small compared to its length; wave height is small means what does it imply? That if I take square or cube of the wave height, it can be neglected small compared to length small. So, the small quantities if you take the square or cube of small quantities, they become still smaller, do you understand?