Proof of `The Euler characteristic of a smooth hypersurface as a binomial tail`

groundedproofs/Lax894236Proofs/EulerCharacteristic.lean · lax-894236

What this proof establishes

no assumptions

Assuming the claims on the left, the claim on the right holds — checked by the archive's pipeline. Proof code is not displayed here.

Read the Lean proof on GitHub

Description

Expand (1d)(n+2)(1 - d)^(n+2) by the binomial theorem and peel off the two lowest terms, 11 and (n+2)d-(n+2) d, which cancel against the rest of chiPolychiPoly.