Journal of Physics A. Mathematical and General vol:39 issue:13 pages:3311-3318
We obtain a lowering operator for multiple orthogonal polynomials having orthogonality conditions with respect to r is an element of N classical weights. These multiple orthogonal polynomials are generalizations of the classical orthogonal polynomials. Combining the lowering operator with the raising operators, which have been obtained earlier in the literature, we then also obtain a linear differential equation of order r + 1.