A musician wearing a black shirt is playing bass guitar while kneeling.
a musician in black
Musician in black is a shorter way to say a musician wearing a black shirt
exists e2 e1 e3 s1 x1 x2 x3 x4 x5.(while(e2,e3) & Actor(e3,x1) & v_kneel(e3) & Theme(e2,x4) & Actor(e2,x1) & v_play(e2) & n_guitar(x4) & of(x4,x5) & n_bass(x5) & Theme(e1,x3) & Actor(e1,x2) & v_wear(e1) & n_shirt(x3) & a_black(s1) & Theme(s1,x3) & (x1 = x2) & n_musician(x1))
exists x1 x2.(a_topic(x1) & in(x1,x2) & n_black(x2) & n_musician(x1))