Two muddy boys swim.
Two clean boys walk.
Muddy is not clean, and you cannot walk while you swim.
exists e1 s1 x1.(Actor(e1,x1) & v_swim(e1) & n_boy(x1) & a_muddy(s1) & Theme(s1,x1) & card_eq_2(x1))
exists e1 s1 x1.(Actor(e1,x1) & v_walk(e1) & n_boy(x1) & a_clean(s1) & Theme(s1,x1) & card_eq_2(x1))