What is under the horse?
The sand is under the horse.
    src        edge_attr  dst
0     0           riding    7
1     0               on    7
2     0   to the left of    4
3     0            above    7
4     1               of    7
5     3            under    7
6     3            below    7
7     4  to the right of    0
8     6               of    6
9     7               on    3
10    7            under    0
11    7               on    6
12    7            above    3