A man in a white shirt plays the drums.
A drummer is drumming.
A man who plays the drums is a drummer, and " is drumming" is a rephrasing of "plays the drums".
exists e1 s1 x1 x2 x3.(n_drum(x3) & Theme(e1,x3) & Actor(e1,x1) & v_play(e1) & in(x1,x2) & n_shirt(x2) & a_white(s1) & Theme(s1,x2) & n_man(x1))
exists e1 x1.(Actor(e1,x1) & v_drum(e1) & n_drummer(x1))