# LIB2-087 — Schur block structure does not force a zero triplet eigenvalue

- class: CLAIM · review_state: PUBLISHED · house_tier: not yet assigned
- labels as printed: math_status NOT_PRINTED · attachment NOT_PRINTED · scorecard tier word none (PDF p.146)
- basis: {"pdf_sha256_prefix": "b64ddcd9e16a6dcd", "release": "Rev33.1_S369"}

## Statement

Schur symmetry supplies singlet–triplet block separation and scalar action λI on each irreducible triplet block, but does not force λ = 0.

## Caution

This correction neither reproduces the separate numerical zeros nor provides an all-orders protection theorem.

## Primary source

Appendix A, §A.7.5, Rev32.1 Schur correction, PDF p.151: "Schur’s lemma ensures the block structure at the algebraic representation level — no singlet–triplet mixing, and scalar action λI on each irreducible triplet block; it does not by itself force λ = 0"

## Machine

- url: /library-v2/LIB2-087/
- content_sha256: bae9a64d75a3e506d792063cb269fbcc83de16a2005980ea8284e03ca9fde6fb
- candidate_ids: C2-114

## Freshness

- BUILD_STAMP S371a · 2026-09-26T22:53Z · master 01d1a5873ede42f5 · cut 9dcc6ce9a8ee3e02
- Declared volatile fields (R36): BUILD_STAMP