Proof of `A selected affine ray determines its moment block` (1st statement)
groundedproofs/Lax342547Proofs/SelectedMoments.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 sandwich entrywise. On the diagonal symmetry cancels its two mixed terms; the Boolean square and moment diagonal identity force the constant row to be the selected affine vector times the constant entry. Substitution in every entry leaves only its point moment.