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