-a^{a1}_{v0} b^{a3,v1}_{a0,a2} c^{v2}_{a4} eta1^{a4}_{a3} eta1^{a2}_{a1} a+(a0) a+(v0) a-(v2) a-(v1)
-a^{a1}_{v0} b^{a3,v1}_{a0,a2} c^{v2}_{a4} lambda2^{a2,a4}_{a1,a3} a+(a0) a+(v0) a-(v2) a-(v1)
-1/2 a^{a1}_{v0} b^{a4,v1}_{a2,a3} c^{v2}_{a0} lambda2^{a2,a3}_{a1,a4} a+(a0) a+(v0) a-(v2) a-(v1)