an old man, with a gray beard, riding his bike
Someone is cycling.
The phrase "cycling." from sentence two is another term for "riding his bike ".
exists e1 s1 s2 x1 x2 x3 x4.(a_topic(x1) & Theme(e1,x4) & Actor(e1,x3) & v_ride(e1) & n_bike(x4) & of(x4,x1) & n_male(x1) & (x1 = x3) & with(x1,x2) & n_beard(x2) & a_gray(s2) & Theme(s2,x2) & n_man(x1) & a_old(s1) & Theme(s1,x1))
exists e1 x1.(Actor(e1,x1) & v_cycle(e1) & n_person(x1))