1/2 a^{a1}_{c0,c1} b^{c3}_{c2,a0,a2} eta1^{a2}_{a1} a+(c0) a+(c1) a+(c2) a+(a0) a-(c3)
-1/2 a^{a0}_{c0,c2} b^{c2}_{c1,a1,a2} a+(c0) a+(c1) a+(a1) a+(a2) a-(a0)
+a^{a1}_{c0,c2} b^{c2}_{c1,a0,a2} eta1^{a2}_{a1} a+(c0) a+(c1) a+(a0)