设A={1,2,3,4},A上有8个相容（自反,对称）关系：
{(1,1),(2,2),(3,3),(4,4)};
{(1,1),(2,2),(3,3),(4,4),(1,2),(2,1)};
{(1,1),(2,2),(3,3),(4,4),(1,3),(3,1)};
{(1,1),(2,2),(3,3),(4,4),(2,3),(3,2)};
{(1,1),(2,2),(3,3),(4,4),(1,2),(2,1),(1,3),(3,1)};
{(1,1),(2,2),(3,3),(4,4),(2,3),(3,2),(1,3),(3,1)};
{(1,1),(2,2),(3,3),(4,4),(1,2),(2,1),(2,3),(3,2)};
{(1,1),(2,2),(3,3),(4,4),(1,2),(2,1),(2,3),(3,2),(1,3),(3,1)}; 设A={1,2,3,4},A上有8个相容（自反,对称）关系：
{(1,1),(2,2),(3,3),(4,4)};
{(1,1),(2,2),(3,3),(4,4),(1,2),(2,1)};
{(1,1),(2,2),(3,3),(4,4),(1,3),(3,1)};
{(1,1),(2,2),(3,3),(4,4),(2,3),(3,2)};
{(1,1),(2,2),(3,3),(4,4),(1,2),(2,1),(1,3),(3,1)};
{(1,1),(2,2),(3,3),(4,4),(2,3),(3,2),(1,3),(3,1)};
{(1,1),(2,2),(3,3),(4,4),(1,2),(2,1),(2,3),(3,2)};
{(1,1),(2,2),(3,3),(4,4),(1,2),(2,1),(2,3),(3,2),(1,3),(3,1)};