“…As an important and active topic in this line of research, the research on the approximation capabilities of single hidden layer feedforward neural networks (SLFNs) has attracted the attention from an increasing number of researchers. Some previous research on this topic can be found in Cybenko [5], Funahashi [7], Hornik et al [9,10,12], Ito [13], Chui and Li [4], Leshno et al [14], Chen et al [1][2][3], Liao et al [15], and so on. These studies show that if the network's activation functions obey an explicit set of assumptions, then the network can indeed be shown to be a universal approximator.…”