There are several trees around the horses.
The trees are outside.
Horses must be outside so trees around the horses are outside.
exists p1 x1 x3.(n_horse(x3) & exists s1 x2.((x1 = x2) & around(x2,x3) & n_tree(x2) & a_several(s1) & Theme(s1,x2)))
exists s1 x1.(n_tree(x1) & Theme(s1,x1) & a_outside(s1))