I was reading over some sources about ANNs, and here I found this diagram of a Recurrent Neural Network (RNN, the source calls it a feedback neural network).
I noticed that a few neurons in this diagram lead to other neurons that are dead ends (have no connections to other neurons). For example, neuron U5 leads to no other neurons, and U9 has a connection to U4, but U4 doesn't have a connection to any other neurons.
Is there a purpose for U5 and U4 to even exist?
Or am I missing something bigger here?