The code correspondence of the paper formula 5？

[deepConnectionism]

I checked the source code and I want to know：

How is this reflected in the code? I can't find it.

I found the code:

class SoftAgg(nn.Module):
    def __init__(self, dim=512, expand=True):
        super(SoftAgg, self).__init__()
        self.dim = dim
        self.expand = expand
        self.f = nn.Linear(self.dim, self.dim)
        self.g = nn.Linear(self.dim, self.dim)
        self.h = nn.Linear(self.dim, self.dim)

    def forward(self, x, ix):
        _, jx = torch.unique(ix, return_inverse=True)
        w = torch_scatter.scatter_softmax(self.g(x), jx, dim=1)
        y = torch_scatter.scatter_sum(self.f(x) * w, jx, dim=1)

        if self.expand:
            return self.h(y)[:,jx]
            
        return self.h(y)

And for:

net = net + self.agg_ij(net, ii*12345 + jj)

Why 12345?