operator) with the additional property that idA ≤ c, where id is the identity function. Similarly, a projection operator k is called a kernel operator if and only if k ≤ idA. An example of an infinitary pointwise relation is pointwise convergence of functions—a sequence of functions with converges pointwise to a function if for each in Notes References For order theory examples: T. S. Blyth, Lattices and Ordered Algebraic Structures, Springer, 2005, . G. Gierz, K. H. Hofmann, K. Keimel, J. D. Lawson, M. Mislove, D. S. Scott: Continuous Lattices and Domains, Cambridge University Press, 2003. Mathematical terminology