One hidden layer approximates continuous functions

Theorem taught in Neural units, part of Statistical learning

One hidden layer approximates continuous functions

Type Theorem
Taught in Neural units
Part Statistical learning

For a continuous target f on [0,1]^p and any \varepsilon>0, there is a finite sum

F(x)=\sum_{q=1}^{l} a_q\,\sigma(w_q^\top x+b_q)

with a continuous sigmoidal activation such that \sup_{x\in[0,1]^p}|F(x)-f(x)|<\varepsilon (Cybenko, 1989, Theorem 2). The output here is a linear combination, not a bounded sigmoid forced to represent arbitrary real values. Results for measurable targets use weaker notions of approximation. They do not assert uniform approximation of every discontinuous function by continuous networks.

Used in

See also

Activation function · Sigmoid function · Artificial neuron · Perceptron learning rule · A single threshold unit cannot compute XOR · History of the neural unit · Neural unit · Linear separability

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