Introduction to ANNs
Neural networks are formed by the integration of several simpler units, called neurons. A neuron is just a representation of the following relation between some inputs 
and one output 
of the form
Here:
is called the bias
is called the weights
is the activation functions
The earliest biological models of the neuron in animals and humans historically use a mathematical formulation similar to the one above, in which dendrites transmit incoming information from synapses, propagating and combining it in the neuron’s axons, which is then connected to the synapses of nearby, connected neurons. However, it is worth stressing that the formula above is an extremely simplified, naive, and (to some extent) poor representation of what really happens in our brains, lacking the more complex time-dependence behaviors produced by the propagation of electric signals. Over the years, researchers have come up with more realistic...
