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