TaylorShift: Shifting the Complexity of Self-Attention from Squared to
  Linear (and Back) using Taylor-Softmax
Tobias Christian Nauen Sebastian Palacio Andreas Dengel
The quadratic complexity of the attention mechanism represents one of the
biggest hurdles for processing long sequences using Transformers. Current
methods, relying on sparse representations or stateful recurrence, sacrifice
token-to-token interactions, which ultimately leads to compromises in
performance. This paper introduces TaylorShift, a novel reformulation of the
Taylor softmax that enables computing full token-to-token interactions in
linear time and space. We analytically determine the crossover points where
employing TaylorShift becomes more efficient than traditional attention,
aligning closely with empirical measurements. Specifically, our findings
demonstrate that TaylorShift enhances memory efficiency for sequences as short
as 800 tokens and accelerates inference for inputs of approximately 1700 tokens
and beyond. For shorter sequences, TaylorShift scales comparably with the
vanilla attention. Furthermore, a classification benchmark across five tasks
involving long sequences reveals no degradation in accuracy when employing
Transformers equipped with TaylorShift. For reproducibility, we provide access
to our code under https://github.com/tobna/TaylorShift.