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