-a^{a1}_{c2} b^{c1,c2}_{c0,a0} c^{v0}_{a2} eta1^{a2}_{a1} a+(c0) a+(a0) a-(v0) a-(c1)
+a^{a1}_{c2} b^{c1,c2}_{c0,a2} c^{v0}_{a0} eta1^{a2}_{a1} a+(c0) a+(a0) a-(v0) a-(c1)