1/2 a^{a0,a1}_{c0,c3} b^{c3,a2}_{c1,c4} c^{c4}_{c2} a+(c0) a+(c1) a+(c2) a-(a2) a-(a1) a-(a0)
-1/4 a^{a0,a1}_{c3,c4} b^{c3,a2}_{c0,c1} c^{c4}_{c2} a+(c0) a+(c1) a+(c2) a-(a2) a-(a1) a-(a0)