+--------------------------------------+
| x x2 nx n_sem |
|--------------------------------------|
1. | a ; b ; c a b c 3 2 |
2. | e; d e d 2 1 |
+--------------------------------------+
+--------------------------------------------+
| x x2 nx n_sem nx2 |
|--------------------------------------------|
1. | a ; b ; c a b c 3 2 2 |
2. | e; d e d 2 1 1 |
+--------------------------------------------+