Activation_Functions.ipynb : Learning rate Notation

[kmouts]

In the text:
"Hence, we effectively implement a function $w^{t} = f(w^{t-1}, g^{t}, ...)$ with 𝑤 being the parameters, and $g^{t} = \nabla_{w^{(t-1)}} \mathcal{L}^{(t)}$ the gradients at time step 𝑡. A common, additional parameter to this function is the learning rate, here denoted by 𝜂. "
There is a discrepancy between symbols $\mathcal{L}$ and 𝜂