a^{a0,v0}_{c0,c3} b^{c2,c3}_{c1,a1} c^{}_{} eta1^{a1}_{a0} a+(c0) a+(c1) a-(v0) a-(c2)
+1/2 a^{a0,v0}_{c1,c2} b^{c1,c2}_{c0,a1} c^{}_{} a+(c0) a+(a1) a-(v0) a-(a0)
+1/2 a^{a0,v0}_{c1,c2} b^{c1,c2}_{c0,a1} c^{}_{} eta1^{a1}_{a0} a+(c0) a-(v0)