T1 — Existence of Minimizers

Hero · Foundation group · Cat A. Source: C-0001 / P-0001. Verification: E-0001, E-0002. Canonical version: CV-1.0. Full statement and proof: Canonical Spec — Part 5 · §13.

Statement#

On the constraint manifold

the energy functional ${\mathcal{E}}_t$ attains its minimum.

Proof idea#

Compactness + continuity. ${\Sigma }_m$ is compact (closed and bounded subset of $[0,1{]}^n$, the unit hypercube intersected with an affine hyperplane). The energy ${\mathcal{E}}_t={\lambda }_{\mathrm{cl}}{\mathcal{E}}_{\mathrm{cl}}+{\lambda }_{\mathrm{sep}}{\mathcal{E}}_{\mathrm{sep}}+{\lambda }_{\mathrm{bd}}{\mathcal{E}}_{\mathrm{bd}}+{\lambda }_{\mathrm{tr}}{\mathcal{E}}_{\mathrm{tr}}$ is continuous in $u$ for the standard provisional operator forms (sigmoid closure, smooth distinction, polynomial double-well). The extreme value theorem gives the existence of a global minimizer. $\square$

Why this is a hero#

T1 is the well-posedness foundation. The entire variational framework of SCC — the four-term energy, the diagnostic vector $\mathbf{d}$, the soft-to-crisp recovery — assumes that minimizers exist. T1 secures that assumption unconditionally. Every subsequent theorem (uniqueness conditions in T6, non-triviality in T8-Core, stability in T7-Enhanced, asymptotic shape in T11) is a refinement of "the minimizer exists, and here is more about it."

The volume constraint ${\Sigma }_m$ is doing real work. Without it, the trivial field $u\equiv 0$ globally minimizes (all energy terms are nonnegative and vanish at $u=0$). T1 only makes sense given the volume constraint; the constraint is not a computational convenience but a structural axiom of the theory.

Logical dependencies#

• Builds on: compactness of ${\Sigma }_m$ (convex polytope structure, Proposition 1.1), continuity of provisional operator forms (Group A–E axioms).
• Builds into: T8-Core (the minimizer is non-trivial under phase transition condition), T8-Full (extends to full energy), T-PreObj-1 (under full SCC, F=1 single-disk minimizer is non-critical — the existence theorem T1 still holds, but its location shifts to F≥2 configurations).

See also#

• Full proof in canonical: Canonical Spec §13 T1 entry
• The volume constraint ${\Sigma }_m$: Canonical Spec Part 3 §8.0
• Why "the minimizer exists" is not the end: T-PreObj-1 hero page — under full SCC, the location of the minimizer turns out to be where pure-${\mathcal{E}}_{\mathrm{bd}}$ critical points fail to be critical.