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, 58 insertions, 0 deletions

diff --git a/results/bp_nopen_30ep_3seed.log b/results/bp_nopen_30ep_3seed.log
new file mode 100644
index 0000000..f88e725
--- /dev/null
+++ b/results/bp_nopen_30ep_3seed.log
@@ -0,0 +1,58 @@
+=== BP no-pen 30ep seed=42 ===
+BP + ‖f‖² penalty: seed=42, lam=0.0, epochs=30
+  ep 1: test_acc=0.3920
+  ep 5: test_acc=0.4950
+  ep 10: test_acc=0.5296
+  ep 15: test_acc=0.5539
+  ep 20: test_acc=0.5721
+  ep 25: test_acc=0.5813
+  ep 30: test_acc=0.5851
+
+FINAL test acc: 0.5851
+Compare to:
+  BP-trainable (3-seed mean):   0.609
+  Penalized DFA lam=1e-2:       0.363
+  DFA-shallow:                  0.349
+
+Margin vs DFA-shallow baseline: +23.61 pp
+  → BP+penalty intermediate; partial capacity loss + residual mode 2
+Saved results/bp_no_penalty_30ep/bp_pen_lam0.0_s42.json
+=== BP no-pen 30ep seed=123 ===
+BP + ‖f‖² penalty: seed=123, lam=0.0, epochs=30
+  ep 1: test_acc=0.3958
+  ep 5: test_acc=0.4851
+  ep 10: test_acc=0.5345
+  ep 15: test_acc=0.5564
+  ep 20: test_acc=0.5748
+  ep 25: test_acc=0.5827
+  ep 30: test_acc=0.5845
+
+FINAL test acc: 0.5845
+Compare to:
+  BP-trainable (3-seed mean):   0.609
+  Penalized DFA lam=1e-2:       0.363
+  DFA-shallow:                  0.349
+
+Margin vs DFA-shallow baseline: +23.55 pp
+  → BP+penalty intermediate; partial capacity loss + residual mode 2
+Saved results/bp_no_penalty_30ep/bp_pen_lam0.0_s123.json
+=== BP no-pen 30ep seed=456 ===
+BP + ‖f‖² penalty: seed=456, lam=0.0, epochs=30
+  ep 1: test_acc=0.3969
+  ep 5: test_acc=0.4957
+  ep 10: test_acc=0.5344
+  ep 15: test_acc=0.5612
+  ep 20: test_acc=0.5716
+  ep 25: test_acc=0.5845
+  ep 30: test_acc=0.5863
+
+FINAL test acc: 0.5863
+Compare to:
+  BP-trainable (3-seed mean):   0.609
+  Penalized DFA lam=1e-2:       0.363
+  DFA-shallow:                  0.349
+
+Margin vs DFA-shallow baseline: +23.73 pp
+  → BP+penalty intermediate; partial capacity loss + residual mode 2
+Saved results/bp_no_penalty_30ep/bp_pen_lam0.0_s456.json
+=== ALL DONE ===