1/2 a^{}_{} b^{a1,v0}_{c0,a0} c^{c1,c2}_{a2,v0} eta1^{a2}_{a1} a+(c0) a+(a0) a-(c2) a-(c1)
+a^{}_{} b^{a1,v0}_{c1,a0} c^{c0,c1}_{a2,v0} a+(a0) a+(a2) a-(a1) a-(c0)
-a^{}_{} b^{a1,v0}_{c1,a0} c^{c0,c1}_{a2,v0} eta1^{a2}_{a1} a+(a0) a-(c0)
+a^{}_{} b^{a1,v0}_{c1,a0} c^{c0,c1}_{a2,v1} eta1^{a2}_{a1} a+(a0) a+(v1) a-(v0) a-(c0)