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