A man without a helmet is riding a red bike.
A man wearing shorts and a t-shirt is riding a bike.
You can wear shorts and a t-shirt with or without wearing a helmet.
exists e1 s1 x1 x2.(Theme(e1,x2) & Actor(e1,x1) & v_ride(e1) & n_bike(x2) & a_red(s1) & Theme(s1,x2) & -exists x3.(with(x1,x3) & n_helmet(x3)) & n_man(x1))
exists e1 e2 x1 x2 x3 x4 x5 x6.(Theme(e2,x6) & Actor(e2,x1) & v_ride(e2) & n_bike(x6) & subset_of(x5,x1) & n_t-shirt(x5) & subset_of(x2,x1) & Theme(e1,x4) & Actor(e1,x3) & v_wear(e1) & n_shorts(x4) & (x2 = x3) & n_man(x2))