Let f be a non-constant elliptic function with respect to a lattice Λ⊂C. Let P⊂C be a fundamental parallelogram and let the degree of f be n. Let a1,…,an denote the zeros of f in P, and let b1,…,bn denote the poles (both with possible repeats). By considering the integral (if required, also slightly perturbing P )
2πi1∫∂Pzf(z)f′(z)dz
show that
j=1∑naj−j=1∑nbj∈Λ
Let ℘(z) denote the Weierstrass ℘-function with respect to Λ. For v,w∈/Λ with ℘(v)=℘(w) we set
f(z)=det⎝⎛1℘(z)℘′(z)1℘(v)℘′(v)1℘(w)℘′(w)⎠⎞
an elliptic function with periods Λ. Suppose z∈/Λ,z−v∈/Λ and z−w∈/Λ. Prove that f(z)=0 if and only if z+v+w∈Λ. [You may use standard properties of the Weierstrass ℘-function provided they are clearly stated.]