The Prenucleolus: 

x1 = 600
x2 = 550
x3 = 50
x4 = 2.5e-05

Excesses:

50 (2 )
50 (1 3 4 )
0 ()
-2.5e-05 (4 )
-2.50001e-05 (2 3 )
-2.50001e-05 (1 4 )
-2.50001e-05 (1 2 3 )
-5.00001e-05 (1 2 3 4 )
-50 (3 )
-50 (1 3 )
-50 (3 4 )
-550 (1 2 )
-550 (2 4 )
-550 (1 2 4 )
-600 (1 )
-600 (2 3 4 )