Title: Multiplier Criteria of Marcinkiewicz Type for Jacobi Expansions
Abstract: It is shown how an integral representation for the product of Jacobi polynomials can be used to derive a certain integral Lipschitz type condition for the Cesà ro kernel for Jacobi expansions. This result is then used to give criteria of Marcinkiewicz type for a sequence to be multiplier of type (p, p), $1 < p < \infty$, for Jacobi expansions.