An engineer is working alone near his machines.
an engineer was working all by himself on the machine
all by himself is a rephrase of alone
exists e1 s1 x1 x2.(near(e1,x2) & n_machine(x2) & of(x2,x1) & n_male(x1) & a_alone(s1) & Manner(e1,s1) & Actor(e1,x1) & v_work(e1) & n_engineer(x1))
exists e1 s1 x1 x2.(n_machine(x2) & on(e1,x2) & by(e1,x1) & n_male(x1) & a_all(s1) & Manner(e1,s1) & Actor(e1,x1) & v_work(e1) & n_engineer(x1))