Students sitting outside in a forest with books and pencils.
The students had their books and pencils and were ready for the outdoor lecture about trees to begin.
Sitting in a forest with books and pencils does not mean that any lecture about any subject (let alone trees specifically) is going to occur.
exists e1 s1 x1 x2 x3 x4 x5 x6.(a_topic(x1) & with(e1,x4) & n_pencil(x6) & n_book(x5) & subset_of(x6,x4) & subset_of(x5,x4) & in(e1,x3) & n_forest(x3) & a_outside(s1) & Manner(e1,s1) & Actor(e1,x2) & v_sit(e1) & (x1 = x2) & n_student(x1))
exists e1 p1 s1 s2 x1 x2 x3 x4 x5 x6.(n_lecture(x5) & a_outdoor(s2) & Theme(s2,x5) & n_student(x1) & n_pencil(x4) & n_book(x3) & subset_of(x4,x2) & subset_of(x3,x2) & of(x2,x1) & n_thing(x1) & for(s1,x5) & about(x5,x6) & Topic(x6,p1) & exists e2 x7.(Theme(e2,x7) & Actor(e2,x6) & v_begin(e2) & n_thing(x7)) & n_tree(x6) & Theme(s1,x1) & a_ready(s1) & Theme(e1,x2) & Actor(e1,x1) & v_have(e1))