Proof of `Independent sets lift and project through a blow-up` (3rd statement)
groundedproofs/Lax263307Proofs/BlowUpIndependentSets.lean · lax-263307
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.
Description
The blow-up graph has exactly the sum of its fibre sizes as its order.
Proof strategy
Apply the finite-type cardinality formula for a dependent sum.
Attribution
Bonnet–Chang, Section 6.