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