Almost everywhere summability of Laguerre series
We apply a construction of generalized twisted convolution to investigate almost everywhere summability of expansions with respect to the orthonormal system of functions , n = 0,1,2,..., in , a ≥ 0. We prove that the Cesàro means of order δ > a + 2/3 of any function , 1 ≤ p ≤ ∞, converge to f a.e. The main tool we use is a Hardy-Littlewood type maximal operator associated with a generalized Euclidean convolution.