Men dressed in either theatrical or historical attire riding horses.
The men are riding four wheelers.
Men ridding horses doesn't have to be riding four wheelers.
exists e1 x1 x2.(a_topic(x1) & all x3.((exists s1 x4 x5.(n_horse(x3) & of(x3,x5) & n_riding(x5) & of(x3,x4) & n_attire(x4) & a_theatrical(s1) & Theme(s1,x3)) | exists s2 x6 x7.(n_horse(x3) & of(x3,x7) & n_riding(x7) & of(x3,x6) & n_attire(x6) & a_historical(s2) & Theme(s2,x3))) -> in(e1,x3)) & Theme(e1,x2) & v_dress(e1) & (x1 = x2) & n_man(x1))
exists e1 x1 x2.(n_man(x1) & Theme(e1,x2) & Actor(e1,x1) & v_ride(e1) & n_wheeler(x2) & card_eq_4(x2))