A very joyous fireman or emergency medical worker.
A very happy human
A fireman or emergency medical worker is a human in a specific occupational role. If someone is very joyous, then we already know that they are very happy - those phrases mean the same thing.
exists s1 s2.(a_topic(s1) & (n_fireman(s1) | exists s3 x1.(n_worker(s1) & a_medical(s3) & Theme(s3,s1) & of(s1,x1) & n_emergency(x1))) & a_joyous(s2) & Theme(s2,s1) & r_very(s1))
exists s1 x1.(a_topic(x1) & n_human(x1) & a_happy(s1) & Theme(s1,x1) & r_very(x1))