PWR-HYBRID-3/journal/journal.tex
Dane Sabo c4297e616c journal: Tikhonov bound derivation for prompt-jump reduction
New entry 2026-04-21-polytopic-sos-tikhonov.tex covering:
  - Polytopic barrier attempt (naive Nagumo check), why it fails
    (safety polytope too large for LQR contraction from anywhere),
    and the Blanchini pre-image algorithm as the right fix.
  - SOS polynomial barrier success on the 2-state reduced projection:
    CSDP returns OPTIMAL on a degree-4 polynomial B(x1, x2). First
    non-quadratic barrier artifact for this plant. Full polynomial
    coefficients embedded.
  - Tikhonov singular-perturbation theorem derivation for the PJ
    reduction. Writes the 10-state PKE in slow-fast form with
    eps=Lambda, identifies the quasi-steady manifold h(x) = PJ
    formula, shows fast subsystem exponentially stable under the
    prompt_critical_margin_heatup invariant. Error bound:
    |x(t) - x_PJ(t)| <= C*Lambda = O(1e-4) in state units, uniform
    after boundary layer. Empirical validation data (0.1% max) is
    consistent with K_1 ~ 40, K_3 ~ 70 problem constants.
  - apass markers for remaining open items: scram entry expansion,
    heatup steam-dump Q_sg, heatup controller-ref mismatch.

The Tikhonov derivation upgrades "we ran it and 0.1% error" to
"bounded by C*Lambda where C depends on problem properties bounded
by the safety halfspaces." Rigorous rate.

Journal: 38 pages, clean build.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
2026-04-21 17:23:20 -04:00

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% journal.tex — top-level document that aggregates all dated entries.
%
% Build:
% cd journal && latexmk -pdf journal.tex
% or individual entry:
% cd journal && latexmk -pdf entries/2026-04-17-controllers-linear-reach.tex
\input{preamble.tex}
\title{HAHACS Lab Journal\\
\large PWR\_HYBRID\_3 preliminary example, invention log}
\author{Dane Sabo, with Claude (Hacker-Split)}
\date{Started \today}
\begin{document}
\maketitle
\tableofcontents
\newpage
\section*{How to read this journal}
Each section is a dated session. Sessions are written in two styles:
\begin{itemize}
\item \textbf{Deep (A-style)}: full invention-log depth. Derivations
in math, code snippets with commentary, figures with long
captions, dead-ends documented, terminal output included where
it changes the story. A reader in 2030 should be able to
rebuild the work from this alone.
\item \textbf{Narrative (B-style)}: end-of-session notes with
pointers. Marked with \apass{some detail} callouts for
content that should be expanded in a later A-pass.
\end{itemize}
\textbf{File-path archaeology note.} Entries dated on or before
2026-04-20 (afternoon) refer to MATLAB files under \texttt{plant-model/}
and a MATLAB-Julia split where Julia code lived under \texttt{julia-port/}.
The 2026-04-20 evening mega-session ported everything to Julia and
deleted MATLAB; the result is the unified \texttt{code/} directory.
Path references in earlier entries are historically accurate for their
date; recover the corresponding sources via \texttt{git log} or the
parent commit at the time.
Callout boxes signal specific content types:
\begin{derivation}
Mathematical derivations — algebra, integrals, limits. Where they
matter to the safety claim, they live here in full.
\end{derivation}
\begin{decision}
Design decisions made during the session, with the rationale and the
alternatives considered.
\end{decision}
\begin{deadend}
Approaches that didn't work and why. These are as valuable as the
working paths — they keep the next explorer from repeating the mistake.
\end{deadend}
\begin{limitation}
Known-approximate or known-broken behavior. Soundness gaps live here.
Each limitation ties to a plan or an open question.
\end{limitation}
\newpage
% ---- Session entries, in chronological order -------------------------------
\input{entries/2026-04-17-controllers-linear-reach.tex}
\newpage
\input{entries/2026-04-20-predicates-boundaries-julia-nonlinear.tex}
\newpage
\input{entries/2026-04-20-evening-mega-session.tex}
\newpage
\input{entries/2026-04-20-overnight-prompt-jump.tex}
\newpage
\input{entries/2026-04-21-polytopic-sos-tikhonov.tex}
\end{document}