The dressed up young people are sitting in chairs while they wait.
The students are waiting for a program to begin.
sitting in chairs doesn't imply  waiting for a program to begin.
exists e1 e2 p1 s1 x1 x2.(n_thing(x1) & n_people(x1) & a_young(s1) & Theme(s1,x1) & r_up(x1) & Theme(e1,x1) & v_dress(e1) & exists e3.(Actor(e3,x1) & v_wait(e3)) & while(e2,p1) & in(e2,x2) & n_chair(x2) & Actor(e2,x1) & v_sit(e2))
exists e1 p1 x1.(n_student(x1) & Topic(e1,p1) & Actor(e1,x1) & v_wait(e1) & exists e2 x2.(Actor(e2,x2) & v_begin(e2) & n_program(x2)))