  Recently, a new stabilizer free weak Galerkin method (SFWG) is proposed,
which is easier to implement. The idea is to raise the degree of polynomials j
for computing weak gradient. It is shown that if j>=j0 for some j0, then SFWG
achieves the optimal rate of convergence. However, large j will cause some
numerical difficulties. To improve the efficiency of SFWG and avoid numerical
locking, in this note, we provide the optimal j0 with rigorous mathematical
proof.
