Table 1 Notations.

From: A recurrent sigma pi sigma neural network

Variables

Definition

\(t\)

Time step

\(P + 1\)

Number of input layer

\(N\)

Number of \(\sum_{1}\) layer

\(Q\)

Number of \(\prod\) layer

\(I(t)\)

overall input at current time step \(t\)

\(I_{p} (t)\)

The p-th element of \(I(t)\)

\(f( \cdot )\)

Activation function

\(y(t - 1)\)

Output value of network at previous time step \(t - 1\)

\(W_{0}\)

Weight vector between \(\sum_{2}\) layer and \(\prod\) layer

\(Q\)

Number of nodes of the \(\prod\) layer

\(w_{0q}\)

The q-th element of \(W_{0}\)

\(W_{n}\)

The n-th weigh vector of \(\sum_{1}\) layer

\(\varepsilon (t)\)

Variable of \(\sum_{1}\) layer at current time step \(t\)

\(\varepsilon_{n} (t)\)

The n-th element of \(\varepsilon (t)\)

\(A_{q}\)

Set of neurons about the \(\sum_{1}\) layer linked with the \(q - th\) neuron of the \(\prod\) layer

\(B_{n}\)

Set of neurons about \(\prod\) layer linked with the \(n - th\) neuron of \(\sum_{1}\) layer

\(a\)

Arbitrary

\(\phi (a)\)

Number of elements in \(a\)

\(\delta (t)\)

Output result of \(\prod\) layer at current time step \(t\)

\(\delta_{q} (t)\)

The q-th element of \(\delta (t)\)

\(y(t)\)

Actual output of RSPSNN at current time step \(t\)