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