Three children, two girls and one boy, in martial art stances, standing on the hard-wood floor of a large room.
Three children await the instructions of their sifu.
Just because there are children, that does not imply that a sifu is around.  Just because the children are in martial art stances, that does not imply that they are awaiting any sort of instruction, as there is no mention of it.
exists e1 s1 s2 s3 x1 x2 x3 x4 x5 x6 x7 x8 x9.(n_floor(x8) & a_hard-wood(s2) & Theme(s2,x8) & a_topic(x1) & rel(x1,x2) & subset_of(x4,x2) & on(e1,x8) & of(x8,x9) & n_room(x9) & a_large(s3) & Theme(s3,x9) & Actor(e1,x7) & v_stand(e1) & (x4 = x7) & in(x4,x5) & n_stance(x5) & of(x5,x6) & n_art(x6) & a_martial(s1) & Theme(s1,x5) & n_boy(x4) & card_eq_1(x4) & subset_of(x3,x2) & n_girl(x3) & card_eq_2(x3) & n_child(x1) & card_eq_3(x1))
exists e1 x1 x2 x3.(n_sifu(x3) & of(x3,x2) & n_thing(x2) & n_instruction(x2) & Theme(e1,x2) & Actor(e1,x1) & v_await(e1) & of(x2,x3) & n_child(x1) & card_eq_3(x1))