A shirtless man is performing some skateboard tricks in front of other skateboarders.
A shirtless skateboarder is doing some tricks in a competition at a skate park.
A man is not necessarily a skateboarder. One does not have to be in a competition because they are performing tricks.
exists e1 s1 x1 x2 x3 x4 x5 x6.(n_skateboarder(x6) & in(e1,x4) & of(x4,x5) & -(x5 = x6) & n_skateboarder(x5) & n_front(x4) & Theme(e1,x2) & Actor(e1,x1) & v_perform(e1) & n_trick(x2) & of(x2,x3) & n_skateboard(x3) & n_man(x1) & a_shirtless(s1) & Theme(s1,x1))
exists e1 s1 x1 x2 x3 x4 x5.(at(e1,x4) & n_park(x4) & of(x4,x5) & n_skate(x5) & Theme(e1,x2) & Actor(e1,x1) & v_do(e1) & in(x2,x3) & n_competition(x3) & n_trick(x2) & n_skateboarder(x1) & a_shirtless(s1) & Theme(s1,x1))