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Comment by iNic

2 months ago

- The Fourier Transform is an invertable operator (i.e. it acts on functions, in the case of matrices both functions and operators are themselves matrices). It transforms into what we call frequency space.

- This is most intuitive for signal analysis or images [1].

- Frequency space is inherently "complex", i.e. represented by complex numbers.

- Frequencies have the advantage that they take a "global" view of the problem.

- This mechanism is not equivalent to the attention mechanism. There is definitely a trade-off.

- But it is possible that it captures many of the important relationships that attention capture.

- I do not have good intuition for modReLU right away, but it seems important because it modifies the frequencies but preserves the inverse Fourier transform.

[1]: https://homepages.inf.ed.ac.uk/rbf/HIPR2/fourier.htm

Worth noting that frequency space is often considered one dimensional. Adding the phase is what gives the other dimension.

modReLU seems to just increase the magnitude of the input value, and rotate it to the original polar angle. With clipping off negative magnitudes.

Or equivalently rotates a (real) bias term with the input angle and adds that into the original.

  (abs(z) + c)*exp(i*arg(z)) = abs(z)*exp(i*arg(z)) + c*exp(i*arg(z)) = z + c*exp(i*arg(z))