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