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