I am reading about a Neural Networks project that has some data like this

alt text

I am new to this, and though I think I understand what a 3:1 network mean, I do not understand what number of inputs (to each neuron) means.

alt text

I think this is what a 3:1 network would look like (please correct me if I am wrong). Does 3 inputs per neuron mean that we will have 3 inputs to each of nodes A, B and C? In that case, what would the line connecting A to Z indicate? As in out of three inputs, how is a resultant chosen?


1 Answer 1


You are bypassing the "hidden layer": A neural network consists of three layers: Input layer, hidden layer, and output layer:

You may also have more than one hidden layer:

(source: mu-sigma.com)

Though, in your case, since the number of hidden layers is not specified, it is safe to assume that there is just 1 hidden layer.

So, for example, in a 3:1 network, you have 1 output neuron, and 3 hidden neurons. The number of inputs shows the number of neurons in the input layer.

  • $\begingroup$ thanks, is it compulsory to have a hidden layer in a neural network? $\endgroup$
    – Lazer
    Sep 21, 2010 at 5:14
  • $\begingroup$ You are welcome! The hidden layer is not mandatory. Though for an ANN to represent any real-world functionality, hidden layers are usually incorporated. $\endgroup$ Sep 21, 2010 at 6:00

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