Hi,

I would like to collapse a serie of 2d convolutions to a single conv operation.

Basically I’d like to make the pytorch convolution associative.

For example if I have something like

y = F.conv2d(F.conv2d(a1,k1),k0)

I’d like to write it this way: y = F.conv2d(a1,K) (where K depends on k1 and k2).

If my calculus are not wrong, this should work:

```
a1 = torch.randn(1,100,256,256)
k1 = torch.randn(25,100,5,5)
k0 = torch.rand(1,25,5,5)
a0 = F.conv2d(a1,k1)
y = F.conv2d(a0,k0)
K = F.conv2d(k1.transpose(0,1),k0,padding=4).transpose(0,1)
y2 = F.conv2d(a1,K)
```

But it doesn’t work.

Does anyone know what I am forgetting ? Thanks