-a^{c1}_{c0} b^{a0}_{c3} c^{c3,v0}_{c2,a1} eta1^{a1}_{a0} a+(c0) a+(c2) a-(v0) a-(c1)
+a^{c0}_{c3} b^{a0}_{c1} c^{c3,v0}_{c2,a1} eta1^{a1}_{a0} a+(c1) a+(c2) a-(v0) a-(c0)