The skateboarder rides the pipe wall at a skater park.
The biker rides the pipe wall at a skater park.
A skateboarder rides a skateboard, whereas a biker rides a bike. One cannot ride both simultaneously.
exists e1 x1 x2 x3 x4 x5.(n_wall(x2) & of(x2,x3) & n_pipe(x3) & n_skateboarder(x1) & at(e1,x4) & n_park(x4) & of(x4,x5) & n_skater(x5) & Theme(e1,x2) & Actor(e1,x1) & v_ride(e1))
exists e1 x1 x2 x3 x4 x5.(n_wall(x2) & of(x2,x3) & n_pipe(x3) & n_biker(x1) & at(e1,x4) & n_park(x4) & of(x4,x5) & n_skater(x5) & Theme(e1,x2) & Actor(e1,x1) & v_ride(e1))