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We define a power series for .
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We shift x by 1 and y by 2, performing all steps three times: all at once, x first, or y first. (In practice, one would typically do both shifts at once: it is computationally more efficient.)
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Let's take a look at the first few homogeneous components of ps_both.
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Now we verify that the three results, ps_both, ps_x_y and ps_y_x, are equal (up to homogeneous degree 20).
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We define a univariate polynomial over power series.
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We apply a Taylor shift by 1, and then by -1 on the result.
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We verify that the result is equal to the original polynomial (up to homogeneous degree 20).
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