“…On the other hand, one can easily check that l χ ∪ l χ = 0, l χ 2 ∪ l χ 2 = 0. Also, it is easy to compute that Also, we need the following identity of modular forms, which is proved in [13]. 1 ) Z/3 ∼ = Jac(W ) Z/3 Note that Jac(W ) is generated by 8 elements 1, x 1 , x 2 1 , x 2 , x 2 2 , x 3 , x 2 3 , x 1 x 2 x 3 and Z/3 acts on variables by multiplication of 3rd root of unity.…”