Proof of `Sparse residual contractions belong to the actual primal pins` (2nd statement)
groundedproofs/Lax342547Proofs/PrimalContractions.lean · lax-342547
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
Expand the matrix contraction entrywise and interchange the finite sums. Each label keeps its selector row factor, with a new base coefficient.