• (5 marks)

    1. State the delta rule for backpropagation learning and indicate the significance of each symbol used in its statement

      Answer: Δwji = η × δj × yi
      where Δwji is the weight change from unit i to unit j, η is the learning rate, δj is the local gradient (whose definition is complex and goes beyond what is required for this question), and yi
      is the input signal to node j.