w⁡(x;a,b,a¯,b¯)⁢pn⁡(x;a,b,a¯,b¯)=1n!⁢δxn⁡(w⁡(x;a+12⁢n,b+12⁢n,a¯+12⁢n,b¯+12⁢n)).