-1/4 a^{a1,a2}_{c0,a0} b^{v0,v1}_{c1,a3} c^{v3}_{v2} lambda2^{a0,a3}_{a1,a2} a+(c0) a+(c1) a+(v2) a-(v3) a-(v1) a-(v0)
+a^{a1,a2}_{c0,a0} b^{v0,v2}_{c1,a3} c^{v1}_{v2} eta1^{a3}_{a2} a+(c0) a+(c1) a+(a0) a-(v1) a-(v0) a-(a1)
-1/2 a^{a1,a2}_{c0,a0} b^{v0,v2}_{c1,a3} c^{v1}_{v2} lambda2^{a0,a3}_{a1,a2} a+(c0) a+(c1) a-(v1) a-(v0)