a^{a0,a2}_{c0,c3} b^{c2,c3}_{c1,v0} c^{a1}_{a3} eta1^{a3}_{a2} a+(c0) a+(c1) a+(v0) a-(a1) a-(a0) a-(c2)
-1/4 a^{a0,a1}_{c1,c2} b^{c1,c2}_{c0,v0} c^{a3}_{a2} a+(c0) a+(a2) a+(v0) a-(a3) a-(a1) a-(a0)
+1/2 a^{a0,a2}_{c1,c2} b^{c1,c2}_{c0,v0} c^{a1}_{a3} eta1^{a3}_{a2} a+(c0) a+(v0) a-(a1) a-(a0)