Perceptrons

• Two-layer directed, weighted graph
  • First layer: input nodes
    • Includes a special "threshold" input; value is fixed at -1.0
  • Second layer: output nodes
• Computing an output
  • For each output
    • For each input with an edge to that output
      • Multiply edge weight by input value
    • Add up all the weights for the output
    • Threshold the output (sigmoid(x) = 1 / (1 + e^-x))
    • If f(x) = sigmoid(x), f'(x) = f(x) * (1 - f(x))