 These methods generalize to yet higher dimensions by adding yet more variables. Although the geometric space we experience physically is limited to three dimensions, conceptually there is no limit to the number of dimensions of abstract mathematical space. Just as a line is a one-dimensional subspace of the two-dimensional plane, and a plane is a two-dimensional subspace of three-dimensional space, each specifiable with an equation, so is a hyperplane a three-dimensional subspace of four-dimensional space, also specifiable with an equation such as \(w = 2x - 7y + z\).