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