In interaction nets, one of the core primitives is the 'wire', which form the edges in the graph. One can think of a wire as like a one-shot channel; it has a 'producer' side, which sends some value across, and a 'consumer' side, which does something with that value.
In that context, then, the inverse operator switches which side of the wire you're talking about. If you have a parameter of type `N32`, you're on the 'consumer side'. But if you have a parameter of type `~N32`, that can be viewed as being the 'producer side' of an `N32` channel. Since `~` just swaps the sides, `~~T` is the same as `T`.
In that context, then, the inverse operator switches which side of the wire you're talking about. If you have a parameter of type `N32`, you're on the 'consumer side'. But if you have a parameter of type `~N32`, that can be viewed as being the 'producer side' of an `N32` channel. Since `~` just swaps the sides, `~~T` is the same as `T`.