∬0<y<x<1Pm,nα,β,γ⁡(x,y)⁢Pj,ℓα,β,γ⁡(x,y)⁢(1-x)α⁢(x-y)β⁢yγ⁢ⅆ⁡x⁢ⅆ⁡y=0,