Information Geometry of contingency table The figure above shows that the family of all 2x2 tables forms a regular tetrahedron.  Any indpenent 2x2 table is included in a ruled surface of the tetrahedron. It is observed that the ruled surface is e-geodesic. The embedding form is visible as in the fugure. Thus the 4 edges shares with the 4 edges of the tetrahedron. The ruled surface may enjoy any specific property in the calss of all surfaces with the boundary condition stated as above?