“…Another approach to the definition of the Levy Laplacian is to define it as the Cesaro mean of the second order directional derivatives along the vectors of some orthonormal basis (see [23,20]). This approach can be also useful in the connection with the Yang-Mills equations (see [28,30,32,35,36]) and instantons (see [29,34]). Different approaches to the Yang-Mills equations based on the parallel transport but not based on the Levy Laplacian were used in [17,15,13,14,8,9].…”