          |     \          |
|        |   *  \                |   *  \         |
|        X   *   Y               X   *   Y        |
|         \  *   |                \  *   |        |
|          \ G   |                 \ H   |        |
|           \    |                  \    |        |
|            \   |                   \   |        |
|             \  |                    \  |        |
|              \ |                     \ |        |
|               \|                      \|        |
|              