1/2 a^{v0}_{a0,a1} b^{a2}_{v0} a+(a0) a+(a1) a-(a2)
+a^{v0}_{a0,a1} b^{a2}_{v0} gamma1^{a1}_{a2} a+(a0)
-a^{v0}_{a0,a1} b^{a2}_{v1} gamma1^{a1}_{a2} a+(a0) a+(v1) a-(v0)