paper v2.31: matched 30-epoch BP/DFA controls (was unsourced 0.609/0.308)

The §5 ¶3 BP-no-penalty value of 0.609 ± 0.004 and DFA-no-penalty value
of 0.308 ± 0.014 turned out to be unsourced — they were carried over
from a hardcoded comment in experiments/bp_with_penalty_control.py
("BP-trainable (3-seed mean): 0.609") that nobody had actually measured
with a matched 30-epoch run.

Ran the missing matched controls under the same recipe as BP+pen
(lam=0, 30 epochs, AdamW 1e-3, wd 0.01, cosine schedule, batch 128,
3 seeds 42/123/456):

  BP no-pen 30ep: per-seed 0.5851, 0.5845, 0.5863  →  0.585 ± 0.001
                  (paper said 0.609 ± 0.004, off by 0.024)
  DFA no-pen 30ep: per-seed 0.3070, 0.2985, 0.2966 →  0.301 ± 0.005
                  (paper said 0.308 ± 0.014)

Also re-grounded DFA+penalty 30ep using the dfa_pen_short 3-seed run
(0.3593, 0.3610, 0.3604 → 0.360 ± 0.001), which is what the deep-cosine
+0.155 figure was computed on. The paper had 0.363 ± 0.001 — that came
from the 100-epoch run, not the 30-epoch run, so it was an apples-to-
oranges comparison with BP+pen 30-ep.

Paper changes (§5 ¶3):
  BP penalty cost:  -8 pp  →  -5.5 pp
  DFA pen rescue:   +5.5 → +5.9 pp
  DFA+pen margin vs frozen: +1.4 → +1.1 pp
  BP-to-DFA gap:     17 → 17.0 pp (unchanged)
  BP-to-SB gap:      7.7 → 7.7 pp (unchanged)
  BP-to-DFA gap is still the lower-bound credit-quality cost claim;
  17 pp gap is unchanged in magnitude.

Also updated:
- §5 ¶1 prose: 0.363 → 0.360, 0.308 → 0.301
- §4 ¶4 prose: DFA+pen 0.363 → 0.360
- Appendix J Table 9 caption: 0.363 → 0.360, +9.0 → +9.3 pp gap to SB
- Appendix L paragraph: +5.5 → +5.9 pp DFA penalty rescue
- Figure 3 panel C bar values + title pen-cost annotation
- New results/matched_30ep_control_summary.json as auditable record

Page layout preserved: 9 main pages + refs p10, 18 total, 0 overfull.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

1 files changed, 3 insertions, 3 deletions

diff --git a/paper/figures/render_fig4_penalty_rescue.py b/paper/figures/render_fig4_penalty_rescue.py
index ad21a12..614698c 100644
--- a/paper/figures/render_fig4_penalty_rescue.py
+++ b/paper/figures/render_fig4_penalty_rescue.py
@@ -32,8 +32,8 @@ rho_err = [0.005, 0.0, 0.011, 0.0, 0.0]
 
 # Panel C: 2x2 capacity-cost control
 methods = ["BP", "DFA"]
-no_pen = [0.609, 0.308]
-with_pen = [0.530, 0.363]
+no_pen = [0.585, 0.301]
+with_pen = [0.530, 0.360]
 shallow = 0.349
 
 fig, axes = plt.subplots(1, 3, figsize=(13, 6.0))
@@ -81,7 +81,7 @@ ax.axhline(shallow, color="black", ls="--", lw=1, label=f"frozen baseline {shall
 ax.set_xticks(xpos)
 ax.set_xticklabels(methods, fontsize=10)
 ax.set_ylabel("test accuracy", fontsize=10)
-ax.set_title("(c) BP+penalty 2$\\times$2 control\n(BP-pen-cost $-8$pp; gap $17$pp $=$ credit quality)", fontsize=10)
+ax.set_title("(c) BP+penalty 2$\\times$2 control\n(BP-pen-cost $-5.5$pp; gap $17$pp $=$ credit quality)", fontsize=10)
 ax.legend(loc="upper right", fontsize=8)
 ax.grid(True, axis="y", alpha=0.3)
 ax.set_ylim(0, 0.7)