A man in red is riding his bicycle.
A man is mountain biking.
Not all biking is on a mountain.
exists e1 x1 x2 x3.(Theme(e1,x3) & Actor(e1,x1) & v_ride(e1) & n_bicycle(x3) & of(x3,x1) & n_male(x1) & in(x1,x2) & n_red(x2) & n_man(x1))
exists p1 x1.(exists x2 x3.((x1 = x2) & n_biking(x2) & of(x2,x3) & n_mountain(x3)) & n_man(x1))