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