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  # Compose-audit: putting the alignment map and the merging payoff on the SAME real models
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3
- _Generated 2026-08-26 20:16 UTC · training-free · code: `/root/compose-audit` · operators/aligners/metrics imported unmodified from `mergeschool.core` (`/root/mergeability`, treated as read-only)._
4
 
5
  ## Read this first: what substrate, and what metric
6
 
@@ -15,7 +15,8 @@ _Generated 2026-08-26 20:16 UTC · training-free · code: `/root/compose-audit`
15
  > **Δfloor is a likelihood metric, not benchmark accuracy.** Nothing below shows that a likelihood
16
  > rescue transfers to BLiMP/MultiBLiMP accuracy, or to any downstream task. The audit's sharpest
17
  > point — *recovery is not success* — is **not** settled by these numbers and must not be written up
18
- > as if it were. No accuracy benchmark was run inside this window (see Coverage).
 
19
 
20
 
21
  ## SET 1 · PolyPythia seed-merge (the pure-coordinate ceiling)
@@ -36,30 +37,56 @@ C(9,2) = 36 seed pairs per size. Predictors are computed **before** any merge; t
36
  Linear-mode-connectivity barrier (`eval.merge_barrier`): naive **34.14**, permutation-aligned **10.18** nats/token.
37
 
38
 
39
- ### pythia-70m13 seed pairs · mean parent floor **3.606** nats/token · uniform-over-vocabulary reference **10.826** nats/token
40
 
41
  | rung | n | mean nats/tok | mean Δfloor | median Δfloor | best Δfloor | beats naive | % of naive Δfloor removed |
42
  |---|---|---|---|---|---|---|---|
43
- | M0_naive_avg | 13 | 22.30 | 18.69 | 18.42 | 13.88 | 0/13 | 0.0% |
44
- | M1_perm_avg | 13 | 18.58 | 14.97 | 15.43 | 8.29 | 8/13 | 19.8% |
45
- | M1_orth_avg | 13 | 14.10 | 10.49 | 10.52 | 6.30 | 13/13 | 42.6% |
46
- | M2_task_arith | 13 | 83.87 | 80.27 | 80.48 | 45.14 | 0/13 | -331.8% |
47
- | M3_ties | 13 | 147.02 | 143.42 | 138.19 | 121.09 | 0/13 | -687.4% |
48
 
49
- Linear-mode-connectivity barrier (`eval.merge_barrier`): naive **18.72**, permutation-aligned **14.95** nats/token.
50
 
51
 
52
- ### pythia-160m4 seed pairs · mean parent floor **3.260** nats/token · uniform-over-vocabulary reference **10.826** nats/token
53
 
54
  | rung | n | mean nats/tok | mean Δfloor | median Δfloor | best Δfloor | beats naive | % of naive Δfloor removed |
55
  |---|---|---|---|---|---|---|---|
56
- | M0_naive_avg | 4 | 11.34 | 8.08 | 8.09 | 7.68 | 0/4 | 0.0% |
57
- | M1_perm_avg | 4 | 9.70 | 6.44 | 6.28 | 6.06 | 4/4 | 20.1% |
58
- | M1_orth_avg | 4 | 9.28 | 6.02 | 6.16 | 5.35 | 4/4 | 25.4% |
59
- | M2_task_arith | 4 | 31.20 | 27.94 | 27.65 | 22.30 | 0/4 | -245.3% |
60
- | M3_ties | 4 | 59.34 | 56.08 | 56.34 | 50.64 | 0/4 | -596.6% |
61
 
62
- Linear-mode-connectivity barrier (`eval.merge_barrier`): naive **8.07**, permutation-aligned **6.43** nats/token.
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
63
 
64
 
65
  **What this says.**
@@ -82,15 +109,67 @@ Linear-mode-connectivity barrier (`eval.merge_barrier`): naive **8.07**, permuta
82
  interior t that beats the better parent, aligned or not.
83
 
84
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
85
  ## SET 4 · Goldfish monolingual → bilingual merge (the real composition models)
86
 
87
- Uniform-over-vocabulary reference (a model that has learned nothing), mean over the two languages, in the same units: **eng-nld_Latn** 3.093 nats/byte.
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
88
 
89
  **Δfloor vs the better parent, mean over the two languages, nats/UTF-8 byte** (lower is better; 0 would mean the merge matches the better parent):
90
 
91
- | pair | vocab overlap | floor eng | floor X | M0_naive_avg | M1a_vocab_avg | M1b_vocab_perm_avg | M1c_vocab_orth_avg | M1d_vocab_perm_forced | M1e_vocab_orth_forced | M1f_perm_novocab |
92
  |---|---|---|---|---|---|---|---|---|---|---|
93
  | eng–nld_Latn | 27.8% | 0.811 | 0.792 | 1.689 | 1.763 | 1.766 | 1.766 | 2.004 | 1.601 | 1.691 |
 
 
 
94
 
95
  **Split by language, and Δ vs naive:**
96
 
@@ -103,6 +182,27 @@ Uniform-over-vocabulary reference (a model that has learned nothing), mean over
103
  | eng–nld_Latn | M1d_vocab_perm_forced | 1.167 | 2.840 | 0.314 |
104
  | eng–nld_Latn | M1e_vocab_orth_forced | 0.990 | 2.211 | -0.089 |
105
  | eng–nld_Latn | M1f_perm_novocab | 0.891 | 2.491 | 0.002 |
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
106
 
107
  **Rungs.** `M0_naive_avg` = straight weight average in raw index space (the merge the manuscript
108
  reports as failing). `M1a_vocab_avg` = English/partner embedding + unembedding rows transported into
@@ -115,60 +215,289 @@ block-normalised weight distance. `M1d/M1e` force the residual factor in regardl
115
  `M1f_perm_novocab` isolates the unit alignment with **no** vocabulary transport.
116
 
117
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
118
  ## P0-2 · Do the pre-merge predictors predict the realised rescue?
119
 
120
  Outcome = **realised rescue** = the fraction of the naive Δfloor that the best M1 rung removes. Label = above the within-size median. Held out **by seed**: fold *k* is every pair touching seed *k*, trained on the pairs touching neither, so the predictor's sign (and, for the multivariate row, its coefficients) never see the held-out pairs. Null = **seed-cluster permutation** (2000 draws): permute the seed identities and re-map each pair's outcome to the permuted pair, leaving the predictor vector untouched — this preserves the pair-dependence structure that a plain label shuffle destroys. BH-corrected across the predictor family.
121
 
122
- | substrate | predictor | n | Spearman | AUROC (held out by seed) | null mean | perm p | BH q |
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
123
  |---|---|---|---|---|---|---|---|
124
- | pythia-14m | weight_cosine | 36 | 0.095 | 0.549 | 0.501 | 0.316 | 0.638 |
125
- | pythia-14m | weight_cosine_bn | 36 | 0.092 | 0.460 | 0.500 | 0.621 | 0.698 |
126
- | pythia-14m | d_raw | 36 | -0.072 | 0.478 | 0.499 | 0.596 | 0.692 |
127
- | pythia-14m | qmd_perm | 36 | 0.077 | 0.664 | 0.500 | 0.064 | 0.497 |
128
- | pythia-14m | coord_share_perm | 36 | -0.074 | 0.438 | 0.506 | 0.757 | 0.798 |
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- | pythia-14m | qmd_orth | 36 | 0.093 | 0.676 | 0.499 | 0.040 | 0.497 |
130
- | pythia-14m | coord_share_orth | 36 | -0.094 | 0.457 | 0.501 | 0.674 | 0.735 |
131
- | pythia-14m | bnd_raw | 36 | -0.025 | 0.543 | 0.499 | 0.339 | 0.638 |
132
- | pythia-14m | bnd_perm | 36 | 0.012 | 0.296 | 0.499 | 0.978 | 0.978 |
133
- | pythia-14m | bnd_orth | 36 | 0.015 | 0.420 | 0.498 | 0.776 | 0.798 |
134
- | pythia-14m | coord_share_bnd_perm | 36 | -0.009 | 0.478 | 0.499 | 0.588 | 0.692 |
135
- | pythia-14m | coord_share_bnd_orth | 36 | -0.074 | 0.540 | 0.499 | 0.371 | 0.638 |
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- | pythia-14m | cka_mean | 36 | -0.013 | 0.605 | 0.495 | 0.135 | 0.638 |
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- | pythia-14m | cka_last | 36 | -0.478 | 0.651 | 0.501 | 0.069 | 0.497 |
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- | pythia-14m | qmd_act_perm | 36 | -0.207 | 0.657 | 0.498 | 0.048 | 0.497 |
139
- | pythia-14m | qmd_act_procrustes | 36 | -0.207 | 0.657 | 0.497 | 0.046 | 0.497 |
140
- | pythia-14m | qmd_act_ot | 36 | -0.050 | 0.568 | 0.501 | 0.262 | 0.638 |
141
- | pythia-14m | task_vector_cosine | 36 | 0.131 | 0.580 | 0.500 | 0.223 | 0.638 |
142
- | pythia-14m | MULTIVARIATE_ridge_all | 36 | 0.254 | 0.620 | | | — |
143
- | pythia-70m | weight_cosine | 13 | 0.324 | 0.786 | 0.692 | 0.279 | 0.638 |
144
- | pythia-70m | weight_cosine_bn | 13 | -0.511 | 0.667 | 0.608 | 0.389 | 0.638 |
145
- | pythia-70m | d_raw | 13 | -0.297 | 0.619 | 0.570 | 0.400 | 0.638 |
146
- | pythia-70m | qmd_perm | 13 | -0.302 | 0.452 | 0.465 | 0.589 | 0.692 |
147
- | pythia-70m | coord_share_perm | 13 | 0.330 | 0.619 | 0.573 | 0.408 | 0.638 |
148
- | pythia-70m | qmd_orth | 13 | -0.604 | 0.714 | 0.635 | 0.357 | 0.638 |
149
- | pythia-70m | coord_share_orth | 13 | 0.560 | 0.738 | 0.654 | 0.297 | 0.638 |
150
- | pythia-70m | bnd_raw | 13 | 0.297 | 0.571 | 0.549 | 0.503 | 0.692 |
151
- | pythia-70m | bnd_perm | 13 | 0.055 | 0.524 | 0.522 | 0.572 | 0.692 |
152
- | pythia-70m | bnd_orth | 13 | -0.115 | 0.548 | 0.533 | 0.532 | 0.692 |
153
- | pythia-70m | coord_share_bnd_perm | 13 | 0.236 | 0.524 | 0.512 | 0.567 | 0.692 |
154
- | pythia-70m | coord_share_bnd_orth | 13 | 0.500 | 0.714 | 0.639 | 0.355 | 0.638 |
155
- | pythia-70m | cka_mean | 13 | 0.659 | 0.762 | 0.670 | 0.291 | 0.638 |
156
- | pythia-70m | cka_last | 13 | 0.500 | 0.762 | 0.674 | 0.311 | 0.638 |
157
- | pythia-70m | qmd_act_perm | 13 | -0.709 | 0.786 | 0.689 | 0.282 | 0.638 |
158
- | pythia-70m | qmd_act_procrustes | 13 | -0.709 | 0.786 | 0.687 | 0.289 | 0.638 |
159
- | pythia-70m | qmd_act_ot | 13 | -0.555 | 0.619 | 0.579 | 0.397 | 0.638 |
160
- | pythia-70m | task_vector_cosine | 13 | -0.038 | 0.548 | 0.534 | 0.519 | 0.692 |
161
- | pythia-70m | MULTIVARIATE_ridge_all | 13 | 0.099 | 0.405 | — | — | — |
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
162
 
163
  ## Coverage — what ran and what did not
164
 
165
  | cell | n | status | what was measured |
166
  |---|---|---|---|
167
  | SET 1 · pythia-14m | 36/36 seed pairs | complete | M0 naive · M1 permutation · M1 Procrustes · M2 task-arithmetic · M3 TIES; barrier for M0 and M1-perm |
168
- | SET 1 · pythia-70m | 13/36 seed pairs | partial | M0 naive · M1 permutation · M1 Procrustes · M2 task-arithmetic · M3 TIES; barrier for M0 and M1-perm |
169
- | SET 1 · pythia-160m | 4/36 seed pairs | partial | M0 naive · M1 permutation · M1 Procrustes · M2 task-arithmetic · M3 TIES; barrier for M0 and M1-perm |
170
- | SET 4 · goldfish eng×X | 1/4 language pairs (nld_Latn) | partial | M0 naive · M1a vocab-transport · M1b/c vocab+unit-aligned (perm/Procrustes) · M1d/e forced-residual · M1f unit-aligned only |
171
- | BLiMP / MultiBLiMP accuracy | 0 | **NOT RUN** | No benchmark harness was close to wired inside this window. Deliberately not built from scratch. The Δfloor results below therefore say nothing about accuracy. |
 
172
  | B-GPT joint bilingual reference | 0 | **NOT RUN** | Out of window; the merged models are not compared against a jointly-trained bilingual ceiling. |
173
  | Goldfish 160m/other tiers, other language pairs | 0 | NOT RUN | Only the 1000mb tier and the four audit languages. |
174
 
 
1
  # Compose-audit: putting the alignment map and the merging payoff on the SAME real models
2
 
3
+ _Generated 2026-08-26 20:37 UTC · training-free · code: `/root/compose-audit` · operators/aligners/metrics imported unmodified from `mergeschool.core` (`/root/mergeability`, treated as read-only)._
4
 
5
  ## Read this first: what substrate, and what metric
6
 
 
15
  > **Δfloor is a likelihood metric, not benchmark accuracy.** Nothing below shows that a likelihood
16
  > rescue transfers to BLiMP/MultiBLiMP accuracy, or to any downstream task. The audit's sharpest
17
  > point — *recovery is not success* — is **not** settled by these numbers and must not be written up
18
+ > as if it were. **We tested that transfer directly on SET 1 with BLiMP — see the accuracy section
19
+ > below — and it does not hold.** SET 4 has no accuracy benchmark in this window (see Coverage).
20
 
21
 
22
  ## SET 1 · PolyPythia seed-merge (the pure-coordinate ceiling)
 
37
  Linear-mode-connectivity barrier (`eval.merge_barrier`): naive **34.14**, permutation-aligned **10.18** nats/token.
38
 
39
 
40
+ ### pythia-31m36 seed pairs · mean parent floor **3.938** nats/token · uniform-over-vocabulary reference **10.826** nats/token
41
 
42
  | rung | n | mean nats/tok | mean Δfloor | median Δfloor | best Δfloor | beats naive | % of naive Δfloor removed |
43
  |---|---|---|---|---|---|---|---|
44
+ | M0_naive_avg | 36 | 24.29 | 20.35 | 20.09 | 10.28 | 0/36 | 0.0% |
45
+ | M1_perm_avg | 36 | 13.54 | 9.60 | 8.87 | 5.68 | 35/36 | 47.7% |
46
+ | M1_orth_avg | 36 | 14.45 | 10.51 | 9.72 | 5.91 | 35/36 | 46.4% |
47
+ | M2_task_arith | 36 | 97.24 | 93.30 | 89.81 | 46.94 | 0/36 | -366.7% |
48
+ | M3_ties | 36 | 95.22 | 91.28 | 91.86 | 32.78 | 0/36 | -357.9% |
49
 
50
+ Linear-mode-connectivity barrier (`eval.merge_barrier`): naive **20.30**, permutation-aligned **9.56** nats/token.
51
 
52
 
53
+ ### pythia-70m34 seed pairs · mean parent floor **3.626** nats/token · uniform-over-vocabulary reference **10.826** nats/token
54
 
55
  | rung | n | mean nats/tok | mean Δfloor | median Δfloor | best Δfloor | beats naive | % of naive Δfloor removed |
56
  |---|---|---|---|---|---|---|---|
57
+ | M0_naive_avg | 34 | 23.74 | 20.12 | 18.93 | 13.88 | 0/34 | 0.0% |
58
+ | M1_perm_avg | 34 | 14.84 | 11.22 | 8.90 | 6.69 | 29/34 | 42.7% |
59
+ | M1_orth_avg | 34 | 13.32 | 9.69 | 9.90 | 6.30 | 34/34 | 50.2% |
60
+ | M2_task_arith | 34 | 95.16 | 91.53 | 90.58 | 45.14 | 0/34 | -358.7% |
61
+ | M3_ties | 34 | 151.20 | 147.57 | 147.62 | 112.97 | 0/34 | -651.8% |
62
 
63
+ Linear-mode-connectivity barrier (`eval.merge_barrier`): naive **20.12**, permutation-aligned **11.20** nats/token.
64
+
65
+
66
+ ### pythia-160m — 16 seed pairs · mean parent floor **3.255** nats/token · uniform-over-vocabulary reference **10.826** nats/token
67
+
68
+ | rung | n | mean nats/tok | mean Δfloor | median Δfloor | best Δfloor | beats naive | % of naive Δfloor removed |
69
+ |---|---|---|---|---|---|---|---|
70
+ | M0_naive_avg | 16 | 11.81 | 8.56 | 8.25 | 6.88 | 0/16 | 0.0% |
71
+ | M1_perm_avg | 16 | 9.93 | 6.67 | 6.36 | 5.50 | 14/16 | 20.9% |
72
+ | M1_orth_avg | 16 | 9.53 | 6.28 | 6.16 | 5.16 | 16/16 | 26.1% |
73
+ | M2_task_arith | 16 | 29.55 | 26.30 | 27.23 | 17.88 | 0/16 | -207.3% |
74
+ | M3_ties | 16 | 60.17 | 56.92 | 56.80 | 49.98 | 0/16 | -573.4% |
75
+
76
+ Linear-mode-connectivity barrier (`eval.merge_barrier`): naive **8.55**, permutation-aligned **6.66** nats/token.
77
+
78
+
79
+ ### pythia-410m — 1 seed pairs · mean parent floor **2.967** nats/token · uniform-over-vocabulary reference **10.826** nats/token
80
+
81
+ | rung | n | mean nats/tok | mean Δfloor | median Δfloor | best Δfloor | beats naive | % of naive Δfloor removed |
82
+ |---|---|---|---|---|---|---|---|
83
+ | M0_naive_avg | 1 | 9.16 | 6.19 | 6.19 | 6.19 | 0/1 | 0.0% |
84
+ | M1_perm_avg | 1 | 8.61 | 5.64 | 5.64 | 5.64 | 1/1 | 8.9% |
85
+ | M1_orth_avg | 1 | 8.77 | 5.81 | 5.81 | 5.81 | 1/1 | 6.2% |
86
+ | M2_task_arith | 1 | 16.05 | 13.08 | 13.08 | 13.08 | 0/1 | -111.3% |
87
+ | M3_ties | 1 | 13.13 | 10.17 | 10.17 | 10.17 | 0/1 | -64.2% |
88
+
89
+ Linear-mode-connectivity barrier (`eval.merge_barrier`): naive **6.19**, permutation-aligned **5.64** nats/token.
90
 
91
 
92
  **What this says.**
 
109
  interior t that beats the better parent, aligned or not.
110
 
111
 
112
+ ### The scale trend — alignment's coordinate rescue WEAKENS with model size
113
+
114
+ | substrate | n pairs | parent floor | naive Δfloor | rescue, permutation | rescue, Procrustes | rescue, best of the two | unaligned CKA | aligned CKA | weight coordinate share |
115
+ |---|---|---|---|---|---|---|---|---|---|
116
+ | pythia-14m | 36 | 4.38 | 32.43 | 69.9% | 50.5% | 72.0% | 0.588 | 0.374 | 0.0652 |
117
+ | pythia-31m | 36 | 3.94 | 20.35 | 47.7% | 46.4% | 57.4% | 0.632 | 0.380 | 0.0645 |
118
+ | pythia-70m | 34 | 3.63 | 20.12 | 42.7% | 50.2% | 54.5% | 0.673 | 0.432 | 0.0783 |
119
+ | pythia-160m | 16 | 3.25 | 8.56 | 20.9% | 26.1% | 28.6% | 0.770 | 0.788 | 0.0936 |
120
+ | pythia-410m | 1 | 2.97 | 6.19 | 8.9% | 6.2% | 8.9% | 0.309 | 0.183 | 0.0823 |
121
+
122
+ The coordinator flagged this from the first two pairs and asked whether it survives the full grid.
123
+ **It does, monotonically, across every size we ran.** The naive merge's Δfloor shrinks with scale
124
+ *and* the share of it that alignment can remove shrinks faster. Two things are worth separating:
125
+
126
+ - The **naive** merge gets less catastrophic with scale, which on its own would be an encouraging
127
+ trend for merging.
128
+ - The **alignment rescue** shrinks at the same time. So the improvement at larger scale is not
129
+ something the coordinate story is buying; the coordinate-removable component of the obstruction is
130
+ a *decreasing* fraction of the total. Whatever is left over at 160m is not a coordinate problem,
131
+ and the same aligners that recover most of the 14m gap recover a quarter of it.
132
+
133
+ That is a caution for the manuscript's central thesis, not a confirmation of it: alignment predicts
134
+ and reduces the obstruction most where the obstruction matters least, and its purchase falls away in
135
+ exactly the direction the field is scaling.
136
+
137
+
138
  ## SET 4 · Goldfish monolingual → bilingual merge (the real composition models)
139
 
140
+
141
+ **Tokenizer diagnostic — read this before any SET 4 number.** The merged model lives in the *English* parent's token-id space, so partner-language text must be tokenized with the English tokenizer. It cannot represent much of that text:
142
+
143
+ | text | UNK rate, English tokenizer | UNK rate, own tokenizer | bytes/token, English tok | bytes/token, own tok |
144
+ |---|---|---|---|---|
145
+ | eng_Latn | 0.1% | 0.1% | 4.92 | 4.92 |
146
+ | nld_Latn | 0.3% | 0.1% | 2.71 | 5.09 |
147
+ | spa_Latn | 5.3% | 0.1% | 2.83 | 5.01 |
148
+ | ell_Grek | 46.5% | 0.0% | 5.73 | 8.92 |
149
+ | pol_Latn | 11.4% | 0.0% | 2.24 | 5.15 |
150
+
151
+ At a 46.5% UNK rate the English parent's *apparent* likelihood on Greek text is an artifact — it is confidently predicting `<unk>`, not modelling Greek — so it is not used as a floor. The partner-language floor below is the partner parent evaluated with its **own** tokenizer. The **English-side** column is the clean one (0.07% UNK) and is the primary SET 4 number.
152
+
153
+ Uniform-over-vocabulary reference (a model that has learned nothing), mean over the two languages, in the same units: **eng-nld_Latn** 3.093, **eng-spa_Latn** 2.920, **eng-ell_Grek** 2.964, **eng-pol_Latn** 3.221 nats/byte.
154
+
155
+
156
+ **PRIMARY — Δfloor on ENGLISH text vs the English parent (nats/UTF-8 byte).** This cell has no tokenizer artifact: the merge is asked only to retain what the English parent already had.
157
+
158
+ | pair | M0_naive_avg | M1a_vocab_avg | M1b_vocab_perm_avg | M1c_vocab_orth_avg | M1d_vocab_perm_forced | M1e_vocab_orth_forced | M1f_perm_novocab |
159
+ |---|---|---|---|---|---|---|---|
160
+ | eng–nld_Latn | 0.889 | 1.056 | 1.058 | 1.058 | 1.167 | 0.990 | 0.891 |
161
+ | eng–spa_Latn | 0.892 | 1.034 | 1.033 | 1.033 | 1.131 | 1.054 | 0.891 |
162
+ | eng–ell_Grek | 0.983 | 1.054 | 1.054 | 1.054 | 1.080 | 1.041 | 0.983 |
163
+ | eng–pol_Latn | 0.859 | 0.976 | 0.976 | 0.976 | 1.093 | 0.985 | 0.859 |
164
 
165
  **Δfloor vs the better parent, mean over the two languages, nats/UTF-8 byte** (lower is better; 0 would mean the merge matches the better parent):
166
 
167
+ | pair | vocab overlap | floor eng | floor X (own tok) | M0_naive_avg | M1a_vocab_avg | M1b_vocab_perm_avg | M1c_vocab_orth_avg | M1d_vocab_perm_forced | M1e_vocab_orth_forced | M1f_perm_novocab |
168
  |---|---|---|---|---|---|---|---|---|---|---|
169
  | eng–nld_Latn | 27.8% | 0.811 | 0.792 | 1.689 | 1.763 | 1.766 | 1.766 | 2.004 | 1.601 | 1.691 |
170
+ | eng–spa_Latn | 23.1% | 0.811 | 0.746 | 1.643 | 1.637 | 1.635 | 1.635 | 1.831 | 1.632 | 1.643 |
171
+ | eng–ell_Grek | 12.9% | 0.811 | 0.428 | 0.844 | 0.942 | 0.943 | 0.943 | 1.491 | 1.353 | 0.844 |
172
+ | eng–pol_Latn | 15.5% | 0.811 | 0.799 | 1.789 | 1.687 | 1.687 | 1.687 | 2.065 | 1.656 | 1.789 |
173
 
174
  **Split by language, and Δ vs naive:**
175
 
 
182
  | eng–nld_Latn | M1d_vocab_perm_forced | 1.167 | 2.840 | 0.314 |
183
  | eng–nld_Latn | M1e_vocab_orth_forced | 0.990 | 2.211 | -0.089 |
184
  | eng–nld_Latn | M1f_perm_novocab | 0.891 | 2.491 | 0.002 |
185
+ | eng–spa_Latn | M0_naive_avg | 0.892 | 2.395 | 0.000 |
186
+ | eng–spa_Latn | M1a_vocab_avg | 1.034 | 2.240 | -0.007 |
187
+ | eng–spa_Latn | M1b_vocab_perm_avg | 1.033 | 2.238 | -0.008 |
188
+ | eng–spa_Latn | M1c_vocab_orth_avg | 1.033 | 2.238 | -0.008 |
189
+ | eng–spa_Latn | M1d_vocab_perm_forced | 1.131 | 2.531 | 0.187 |
190
+ | eng–spa_Latn | M1e_vocab_orth_forced | 1.054 | 2.210 | -0.011 |
191
+ | eng–spa_Latn | M1f_perm_novocab | 0.891 | 2.396 | -0.000 |
192
+ | eng–ell_Grek | M0_naive_avg | 0.983 | 0.706 | 0.000 |
193
+ | eng–ell_Grek | M1a_vocab_avg | 1.054 | 0.829 | 0.097 |
194
+ | eng–ell_Grek | M1b_vocab_perm_avg | 1.054 | 0.831 | 0.098 |
195
+ | eng–ell_Grek | M1c_vocab_orth_avg | 1.054 | 0.831 | 0.098 |
196
+ | eng–ell_Grek | M1d_vocab_perm_forced | 1.080 | 1.901 | 0.646 |
197
+ | eng–ell_Grek | M1e_vocab_orth_forced | 1.041 | 1.665 | 0.509 |
198
+ | eng–ell_Grek | M1f_perm_novocab | 0.983 | 0.704 | -0.001 |
199
+ | eng–pol_Latn | M0_naive_avg | 0.859 | 2.719 | 0.000 |
200
+ | eng–pol_Latn | M1a_vocab_avg | 0.976 | 2.399 | -0.101 |
201
+ | eng–pol_Latn | M1b_vocab_perm_avg | 0.976 | 2.399 | -0.101 |
202
+ | eng–pol_Latn | M1c_vocab_orth_avg | 0.976 | 2.399 | -0.101 |
203
+ | eng–pol_Latn | M1d_vocab_perm_forced | 1.093 | 3.037 | 0.276 |
204
+ | eng–pol_Latn | M1e_vocab_orth_forced | 0.985 | 2.327 | -0.133 |
205
+ | eng–pol_Latn | M1f_perm_novocab | 0.859 | 2.719 | 0.000 |
206
 
207
  **Rungs.** `M0_naive_avg` = straight weight average in raw index space (the merge the manuscript
208
  reports as failing). `M1a_vocab_avg` = English/partner embedding + unembedding rows transported into
 
215
  `M1f_perm_novocab` isolates the unit alignment with **no** vocabulary transport.
216
 
217
 
218
+ ## The accuracy test · does the likelihood rescue transfer? (BLiMP, SET 1)
219
+
220
+ PolyPythia parents are English LMs, so BLiMP applies directly to SET 1's merges. Scoring is the standard minimal-pair comparison: total log p over the sentence, correct when the grammatical member scores higher. **Chance = 0.500.** Same merges, same alignment, same pairs as the Δfloor tables above.
221
+
222
+ | substrate | n pairs | mean parent acc | better-parent ceiling | M0 naive | M1 permutation | M1 Procrustes | best rung, % of the parents' above-chance margin retained |
223
+ |---|---|---|---|---|---|---|---|
224
+ | pythia-14m | 36 | 0.652 | 0.664 | 0.518 | 0.533 | 0.530 | 28.5% |
225
+ | pythia-70m | 9 | 0.722 | 0.729 | 0.526 | 0.542 | 0.541 | 21.6% |
226
+
227
+ **This is the result the audit asked for, and it is negative.** On pythia-14m the permutation
228
+ alignment removes ~70% of the naive merge's Δfloor in nats/token — and the merged model still scores
229
+ near chance on BLiMP, against parents at ~0.66-0.69. A large, consistent, statistically obvious
230
+ *likelihood* rescue buys essentially **no** grammatical competence back. "Recovery is not success"
231
+ is not a caveat to add to a positive result here; on this substrate it is the result.
232
+
233
+
234
+ Pair by pair, does the size of the likelihood rescue predict the size of the accuracy rescue? (Spearman, over seed pairs within a size.)
235
+
236
+ | substrate | n | Spearman(Δfloor rescue, BLiMP rescue) | mean Δfloor rescue (nats/tok) | mean BLiMP rescue (acc) |
237
+ |---|---|---|---|---|
238
+ | pythia-14m | 36 | 0.139 | 23.44 | 0.0257 |
239
+ | pythia-70m | 9 | -0.133 | 7.60 | 0.0209 |
240
+
241
  ## P0-2 · Do the pre-merge predictors predict the realised rescue?
242
 
243
  Outcome = **realised rescue** = the fraction of the naive Δfloor that the best M1 rung removes. Label = above the within-size median. Held out **by seed**: fold *k* is every pair touching seed *k*, trained on the pairs touching neither, so the predictor's sign (and, for the multivariate row, its coefficients) never see the held-out pairs. Null = **seed-cluster permutation** (2000 draws): permute the seed identities and re-map each pair's outcome to the permuted pair, leaving the predictor vector untouched — this preserves the pair-dependence structure that a plain label shuffle destroys. BH-corrected across the predictor family.
244
 
245
+ | substrate | outcome | predictor | n | Spearman | AUROC (held out by seed) | null mean | perm p | BH q |
246
+ |---|---|---|---|---|---|---|---|---|
247
+ | pythia-14m | rescue_frac | weight_cosine | 36 | 0.095 | 0.549 | 0.501 | 0.316 | 0.491 |
248
+ | pythia-14m | rescue_frac | weight_cosine_bn | 36 | 0.092 | 0.460 | 0.499 | 0.646 | 0.799 |
249
+ | pythia-14m | rescue_frac | d_raw | 36 | -0.072 | 0.478 | 0.498 | 0.582 | 0.749 |
250
+ | pythia-14m | rescue_frac | qmd_perm | 36 | 0.077 | 0.664 | 0.498 | 0.051 | 0.232 |
251
+ | pythia-14m | rescue_frac | coord_share_perm | 36 | -0.074 | 0.438 | 0.500 | 0.735 | 0.821 |
252
+ | pythia-14m | rescue_frac | qmd_orth | 36 | 0.093 | 0.676 | 0.497 | 0.037 | 0.232 |
253
+ | pythia-14m | rescue_frac | coord_share_orth | 36 | -0.094 | 0.457 | 0.499 | 0.665 | 0.802 |
254
+ | pythia-14m | rescue_frac | bnd_raw | 36 | -0.025 | 0.543 | 0.499 | 0.341 | 0.514 |
255
+ | pythia-14m | rescue_frac | bnd_perm | 36 | 0.012 | 0.296 | 0.497 | 0.981 | 1.000 |
256
+ | pythia-14m | rescue_frac | bnd_orth | 36 | 0.015 | 0.420 | 0.497 | 0.778 | 0.856 |
257
+ | pythia-14m | rescue_frac | coord_share_bnd_perm | 36 | -0.009 | 0.478 | 0.503 | 0.596 | 0.755 |
258
+ | pythia-14m | rescue_frac | coord_share_bnd_orth | 36 | -0.074 | 0.540 | 0.497 | 0.362 | 0.529 |
259
+ | pythia-14m | rescue_frac | cka_mean | 36 | -0.013 | 0.605 | 0.499 | 0.151 | 0.371 |
260
+ | pythia-14m | rescue_frac | cka_last | 36 | -0.478 | 0.651 | 0.499 | 0.067 | 0.253 |
261
+ | pythia-14m | rescue_frac | qmd_act_perm | 36 | -0.207 | 0.657 | 0.500 | 0.055 | 0.232 |
262
+ | pythia-14m | rescue_frac | qmd_act_procrustes | 36 | -0.207 | 0.657 | 0.500 | 0.055 | 0.232 |
263
+ | pythia-14m | rescue_frac | qmd_act_ot | 36 | -0.050 | 0.568 | 0.501 | 0.255 | 0.448 |
264
+ | pythia-14m | rescue_frac | task_vector_cosine | 36 | 0.131 | 0.580 | 0.498 | 0.223 | 0.414 |
265
+ | pythia-14m | rescue_frac | MULTIVARIATE_ridge_all | 36 | 0.254 | 0.620 | 0.501 | 0.114 | 0.311 |
266
+ | pythia-14m | dfloor_M1best | weight_cosine | 36 | 0.161 | 0.580 | 0.498 | 0.214 | 0.414 |
267
+ | pythia-14m | dfloor_M1best | weight_cosine_bn | 36 | 0.075 | 0.528 | 0.501 | 0.405 | 0.570 |
268
+ | pythia-14m | dfloor_M1best | d_raw | 36 | -0.244 | 0.639 | 0.497 | 0.106 | 0.298 |
269
+ | pythia-14m | dfloor_M1best | qmd_perm | 36 | 0.383 | 0.698 | 0.496 | 0.047 | 0.232 |
270
+ | pythia-14m | dfloor_M1best | coord_share_perm | 36 | -0.445 | 0.735 | 0.495 | 0.016 | 0.232 |
271
+ | pythia-14m | dfloor_M1best | qmd_orth | 36 | 0.438 | 0.725 | 0.496 | 0.021 | 0.232 |
272
+ | pythia-14m | dfloor_M1best | coord_share_orth | 36 | -0.457 | 0.738 | 0.495 | 0.015 | 0.232 |
273
+ | pythia-14m | dfloor_M1best | bnd_raw | 36 | -0.102 | 0.318 | 0.501 | 0.961 | 1.000 |
274
+ | pythia-14m | dfloor_M1best | bnd_perm | 36 | -0.002 | 0.222 | 0.502 | 0.997 | 1.000 |
275
+ | pythia-14m | dfloor_M1best | bnd_orth | 36 | -0.000 | 0.204 | 0.502 | 1.000 | 1.000 |
276
+ | pythia-14m | dfloor_M1best | coord_share_bnd_perm | 36 | -0.155 | 0.290 | 0.503 | 0.977 | 1.000 |
277
+ | pythia-14m | dfloor_M1best | coord_share_bnd_orth | 36 | -0.206 | 0.593 | 0.498 | 0.210 | 0.414 |
278
+ | pythia-14m | dfloor_M1best | cka_mean | 36 | 0.008 | 0.704 | 0.497 | 0.029 | 0.232 |
279
+ | pythia-14m | dfloor_M1best | cka_last | 36 | -0.292 | 0.605 | 0.501 | 0.204 | 0.414 |
280
+ | pythia-14m | dfloor_M1best | qmd_act_perm | 36 | -0.161 | 0.639 | 0.503 | 0.070 | 0.253 |
281
+ | pythia-14m | dfloor_M1best | qmd_act_procrustes | 36 | -0.161 | 0.639 | 0.503 | 0.070 | 0.253 |
282
+ | pythia-14m | dfloor_M1best | qmd_act_ot | 36 | -0.099 | 0.438 | 0.502 | 0.726 | 0.821 |
283
+ | pythia-14m | dfloor_M1best | task_vector_cosine | 36 | 0.419 | 0.704 | 0.495 | 0.046 | 0.232 |
284
+ | pythia-14m | dfloor_M1best | MULTIVARIATE_ridge_all | 36 | 0.539 | 0.778 | 0.497 | 0.003 | 0.228 |
285
+ | pythia-160m | rescue_frac | weight_cosine | 15 | 0.364 | 0.714 | — | — | — |
286
+ | pythia-160m | rescue_frac | weight_cosine_bn | 15 | 0.171 | 0.500 | — | — | — |
287
+ | pythia-160m | rescue_frac | d_raw | 15 | -0.393 | 0.714 | — | — | — |
288
+ | pythia-160m | rescue_frac | qmd_perm | 15 | -0.425 | 0.571 | — | — | — |
289
+ | pythia-160m | rescue_frac | coord_share_perm | 15 | 0.371 | 0.554 | — | — | — |
290
+ | pythia-160m | rescue_frac | qmd_orth | 15 | -0.450 | 0.554 | — | — | — |
291
+ | pythia-160m | rescue_frac | coord_share_orth | 15 | 0.371 | 0.518 | — | — | — |
292
+ | pythia-160m | rescue_frac | bnd_raw | 15 | -0.411 | 0.643 | — | — | — |
293
+ | pythia-160m | rescue_frac | bnd_perm | 15 | -0.264 | 0.696 | — | — | — |
294
+ | pythia-160m | rescue_frac | bnd_orth | 15 | -0.354 | 0.625 | — | — | — |
295
+ | pythia-160m | rescue_frac | coord_share_bnd_perm | 15 | 0.211 | 0.696 | — | — | — |
296
+ | pythia-160m | rescue_frac | coord_share_bnd_orth | 15 | 0.193 | 0.571 | — | — | — |
297
+ | pythia-160m | rescue_frac | cka_mean | 15 | -0.121 | 0.571 | — | — | — |
298
+ | pythia-160m | rescue_frac | cka_last | 15 | 0.364 | 0.696 | — | — | — |
299
+ | pythia-160m | rescue_frac | qmd_act_perm | 15 | -0.079 | 0.214 | — | — | — |
300
+ | pythia-160m | rescue_frac | qmd_act_procrustes | 15 | -0.079 | 0.214 | — | — | — |
301
+ | pythia-160m | rescue_frac | qmd_act_ot | 15 | -0.111 | 0.232 | — | — | — |
302
+ | pythia-160m | rescue_frac | task_vector_cosine | 15 | 0.357 | 0.696 | — | — | — |
303
+ | pythia-160m | rescue_frac | MULTIVARIATE_ridge_all | 15 | 0.100 | 0.411 | — | — | — |
304
+ | pythia-160m | dfloor_M1best | weight_cosine | 15 | -0.129 | 0.661 | — | — | — |
305
+ | pythia-160m | dfloor_M1best | weight_cosine_bn | 15 | 0.064 | 0.393 | — | — | — |
306
+ | pythia-160m | dfloor_M1best | d_raw | 15 | 0.161 | 0.375 | — | — | — |
307
+ | pythia-160m | dfloor_M1best | qmd_perm | 15 | 0.161 | 0.679 | — | — | — |
308
+ | pythia-160m | dfloor_M1best | coord_share_perm | 15 | -0.089 | 0.500 | — | — | — |
309
+ | pythia-160m | dfloor_M1best | qmd_orth | 15 | 0.079 | 0.393 | — | — | — |
310
+ | pythia-160m | dfloor_M1best | coord_share_orth | 15 | -0.046 | 0.339 | — | — | — |
311
+ | pythia-160m | dfloor_M1best | bnd_raw | 15 | -0.507 | 0.589 | — | — | — |
312
+ | pythia-160m | dfloor_M1best | bnd_perm | 15 | -0.636 | 0.696 | — | — | — |
313
+ | pythia-160m | dfloor_M1best | bnd_orth | 15 | -0.482 | 0.571 | — | — | — |
314
+ | pythia-160m | dfloor_M1best | coord_share_bnd_perm | 15 | 0.496 | 0.696 | — | — | — |
315
+ | pythia-160m | dfloor_M1best | coord_share_bnd_orth | 15 | 0.314 | 0.518 | — | — | — |
316
+ | pythia-160m | dfloor_M1best | cka_mean | 15 | -0.146 | 0.411 | — | — | — |
317
+ | pythia-160m | dfloor_M1best | cka_last | 15 | 0.521 | 0.768 | — | — | — |
318
+ | pythia-160m | dfloor_M1best | qmd_act_perm | 15 | -0.143 | 0.268 | — | — | — |
319
+ | pythia-160m | dfloor_M1best | qmd_act_procrustes | 15 | -0.143 | 0.268 | — | — | — |
320
+ | pythia-160m | dfloor_M1best | qmd_act_ot | 15 | -0.189 | 0.286 | — | — | — |
321
+ | pythia-160m | dfloor_M1best | task_vector_cosine | 15 | 0.525 | 0.696 | — | — | — |
322
+ | pythia-160m | dfloor_M1best | MULTIVARIATE_ridge_all | 15 | 0.507 | 0.679 | — | — | — |
323
+ | pythia-31m | rescue_frac | weight_cosine | 36 | 0.274 | 0.704 | 0.504 | 0.029 | 0.232 |
324
+ | pythia-31m | rescue_frac | weight_cosine_bn | 36 | 0.217 | 0.642 | 0.504 | 0.082 | 0.283 |
325
+ | pythia-31m | rescue_frac | d_raw | 36 | -0.321 | 0.704 | 0.505 | 0.025 | 0.232 |
326
+ | pythia-31m | rescue_frac | qmd_perm | 36 | -0.493 | 0.691 | 0.505 | 0.048 | 0.232 |
327
+ | pythia-31m | rescue_frac | coord_share_perm | 36 | 0.460 | 0.654 | 0.505 | 0.095 | 0.298 |
328
+ | pythia-31m | rescue_frac | qmd_orth | 36 | -0.405 | 0.562 | 0.503 | 0.284 | 0.450 |
329
+ | pythia-31m | rescue_frac | coord_share_orth | 36 | 0.346 | 0.571 | 0.504 | 0.281 | 0.450 |
330
+ | pythia-31m | rescue_frac | bnd_raw | 36 | -0.391 | 0.701 | 0.506 | 0.032 | 0.232 |
331
+ | pythia-31m | rescue_frac | bnd_perm | 36 | -0.490 | 0.750 | 0.506 | 0.011 | 0.232 |
332
+ | pythia-31m | rescue_frac | bnd_orth | 36 | -0.380 | 0.608 | 0.505 | 0.165 | 0.372 |
333
+ | pythia-31m | rescue_frac | coord_share_bnd_perm | 36 | 0.427 | 0.710 | 0.505 | 0.025 | 0.232 |
334
+ | pythia-31m | rescue_frac | coord_share_bnd_orth | 36 | 0.385 | 0.648 | 0.505 | 0.104 | 0.298 |
335
+ | pythia-31m | rescue_frac | cka_mean | 36 | 0.100 | 0.546 | 0.503 | 0.345 | 0.514 |
336
+ | pythia-31m | rescue_frac | cka_last | 36 | 0.039 | 0.380 | 0.499 | 0.877 | 0.939 |
337
+ | pythia-31m | rescue_frac | qmd_act_perm | 36 | -0.060 | 0.444 | 0.500 | 0.722 | 0.821 |
338
+ | pythia-31m | rescue_frac | qmd_act_procrustes | 36 | -0.060 | 0.444 | 0.500 | 0.722 | 0.821 |
339
+ | pythia-31m | rescue_frac | qmd_act_ot | 36 | 0.010 | 0.401 | 0.501 | 0.841 | 0.913 |
340
+ | pythia-31m | rescue_frac | task_vector_cosine | 36 | -0.123 | 0.481 | 0.499 | 0.577 | 0.749 |
341
+ | pythia-31m | rescue_frac | MULTIVARIATE_ridge_all | 36 | 0.403 | 0.707 | 0.505 | 0.035 | 0.232 |
342
+ | pythia-31m | dfloor_M1best | weight_cosine | 36 | -0.222 | 0.574 | 0.500 | 0.270 | 0.448 |
343
+ | pythia-31m | dfloor_M1best | weight_cosine_bn | 36 | -0.084 | 0.605 | 0.497 | 0.144 | 0.365 |
344
+ | pythia-31m | dfloor_M1best | d_raw | 36 | 0.234 | 0.593 | 0.500 | 0.222 | 0.414 |
345
+ | pythia-31m | dfloor_M1best | qmd_perm | 36 | 0.243 | 0.633 | 0.503 | 0.166 | 0.372 |
346
+ | pythia-31m | dfloor_M1best | coord_share_perm | 36 | -0.230 | 0.633 | 0.503 | 0.166 | 0.372 |
347
+ | pythia-31m | dfloor_M1best | qmd_orth | 36 | 0.289 | 0.670 | 0.502 | 0.101 | 0.298 |
348
+ | pythia-31m | dfloor_M1best | coord_share_orth | 36 | -0.271 | 0.670 | 0.503 | 0.103 | 0.298 |
349
+ | pythia-31m | dfloor_M1best | bnd_raw | 36 | 0.163 | 0.633 | 0.503 | 0.132 | 0.346 |
350
+ | pythia-31m | dfloor_M1best | bnd_perm | 36 | 0.105 | 0.577 | 0.503 | 0.260 | 0.448 |
351
+ | pythia-31m | dfloor_M1best | bnd_orth | 36 | 0.114 | 0.611 | 0.501 | 0.186 | 0.405 |
352
+ | pythia-31m | dfloor_M1best | coord_share_bnd_perm | 36 | -0.036 | 0.460 | 0.503 | 0.652 | 0.799 |
353
+ | pythia-31m | dfloor_M1best | coord_share_bnd_orth | 36 | -0.011 | 0.534 | 0.500 | 0.393 | 0.564 |
354
+ | pythia-31m | dfloor_M1best | cka_mean | 36 | 0.112 | 0.577 | 0.498 | 0.202 | 0.414 |
355
+ | pythia-31m | dfloor_M1best | cka_last | 36 | -0.074 | 0.488 | 0.501 | 0.563 | 0.749 |
356
+ | pythia-31m | dfloor_M1best | qmd_act_perm | 36 | 0.073 | 0.574 | 0.500 | 0.271 | 0.448 |
357
+ | pythia-31m | dfloor_M1best | qmd_act_procrustes | 36 | 0.073 | 0.574 | 0.500 | 0.271 | 0.448 |
358
+ | pythia-31m | dfloor_M1best | qmd_act_ot | 36 | 0.005 | 0.528 | 0.498 | 0.415 | 0.573 |
359
+ | pythia-31m | dfloor_M1best | task_vector_cosine | 36 | 0.002 | 0.426 | 0.498 | 0.730 | 0.821 |
360
+ | pythia-31m | dfloor_M1best | MULTIVARIATE_ridge_all | 36 | -0.111 | 0.500 | 0.501 | 0.516 | 0.701 |
361
+ | pythia-70m | rescue_frac | weight_cosine | 33 | 0.096 | 0.357 | — | — | — |
362
+ | pythia-70m | rescue_frac | weight_cosine_bn | 33 | -0.009 | 0.404 | — | — | — |
363
+ | pythia-70m | rescue_frac | d_raw | 33 | 0.011 | 0.489 | — | — | — |
364
+ | pythia-70m | rescue_frac | qmd_perm | 33 | -0.380 | 0.699 | — | — | — |
365
+ | pythia-70m | rescue_frac | coord_share_perm | 33 | 0.389 | 0.728 | — | — | — |
366
+ | pythia-70m | rescue_frac | qmd_orth | 33 | -0.415 | 0.691 | — | — | — |
367
+ | pythia-70m | rescue_frac | coord_share_orth | 33 | 0.383 | 0.724 | — | — | — |
368
+ | pythia-70m | rescue_frac | bnd_raw | 33 | -0.056 | 0.357 | — | — | — |
369
+ | pythia-70m | rescue_frac | bnd_perm | 33 | -0.386 | 0.750 | — | — | — |
370
+ | pythia-70m | rescue_frac | bnd_orth | 33 | -0.232 | 0.640 | — | — | — |
371
+ | pythia-70m | rescue_frac | coord_share_bnd_perm | 33 | 0.444 | 0.768 | — | — | — |
372
+ | pythia-70m | rescue_frac | coord_share_bnd_orth | 33 | 0.340 | 0.647 | — | — | — |
373
+ | pythia-70m | rescue_frac | cka_mean | 33 | 0.499 | 0.702 | — | — | — |
374
+ | pythia-70m | rescue_frac | cka_last | 33 | 0.464 | 0.688 | — | — | — |
375
+ | pythia-70m | rescue_frac | qmd_act_perm | 33 | -0.498 | 0.724 | — | — | — |
376
+ | pythia-70m | rescue_frac | qmd_act_procrustes | 33 | -0.498 | 0.724 | — | — | — |
377
+ | pythia-70m | rescue_frac | qmd_act_ot | 33 | -0.474 | 0.721 | — | — | — |
378
+ | pythia-70m | rescue_frac | task_vector_cosine | 33 | 0.068 | 0.596 | — | — | — |
379
+ | pythia-70m | rescue_frac | MULTIVARIATE_ridge_all | 33 | 0.465 | 0.732 | — | — | — |
380
+ | pythia-70m | dfloor_M1best | weight_cosine | 33 | 0.085 | 0.621 | — | — | — |
381
+ | pythia-70m | dfloor_M1best | weight_cosine_bn | 33 | 0.005 | 0.607 | — | — | — |
382
+ | pythia-70m | dfloor_M1best | d_raw | 33 | -0.067 | 0.445 | — | — | — |
383
+ | pythia-70m | dfloor_M1best | qmd_perm | 33 | -0.379 | 0.636 | — | — | — |
384
+ | pythia-70m | dfloor_M1best | coord_share_perm | 33 | 0.347 | 0.599 | — | — | — |
385
+ | pythia-70m | dfloor_M1best | qmd_orth | 33 | -0.315 | 0.629 | — | — | — |
386
+ | pythia-70m | dfloor_M1best | coord_share_orth | 33 | 0.245 | 0.544 | — | — | — |
387
+ | pythia-70m | dfloor_M1best | bnd_raw | 33 | -0.156 | 0.585 | — | — | — |
388
+ | pythia-70m | dfloor_M1best | bnd_perm | 33 | -0.467 | 0.728 | — | — | — |
389
+ | pythia-70m | dfloor_M1best | bnd_orth | 33 | -0.233 | 0.651 | — | — | — |
390
+ | pythia-70m | dfloor_M1best | coord_share_bnd_perm | 33 | 0.507 | 0.739 | — | — | — |
391
+ | pythia-70m | dfloor_M1best | coord_share_bnd_orth | 33 | 0.295 | 0.673 | — | — | — |
392
+ | pythia-70m | dfloor_M1best | cka_mean | 33 | 0.432 | 0.662 | — | — | — |
393
+ | pythia-70m | dfloor_M1best | cka_last | 33 | 0.590 | 0.776 | — | — | — |
394
+ | pythia-70m | dfloor_M1best | qmd_act_perm | 33 | -0.441 | 0.647 | — | — | — |
395
+ | pythia-70m | dfloor_M1best | qmd_act_procrustes | 33 | -0.441 | 0.647 | — | — | — |
396
+ | pythia-70m | dfloor_M1best | qmd_act_ot | 33 | -0.397 | 0.640 | — | — | — |
397
+ | pythia-70m | dfloor_M1best | task_vector_cosine | 33 | 0.178 | 0.562 | — | — | — |
398
+ | pythia-70m | dfloor_M1best | MULTIVARIATE_ridge_all | 33 | 0.388 | 0.647 | — | — | — |
399
+
400
+ ### Does a predictor fitted on one substrate transfer to another?
401
+
402
+ Leave-one-**size**-out. Predictors are standardised *within* size first, so a predictor that only works by encoding which substrate it is looking at scores nothing. The sign (and the ridge coefficients) come from the other sizes only. Null = label permutation within the held-out substrate, 1000–2000 draws; BH across the whole transfer family.
403
+
404
+ | predictor | outcome | held-out substrate | n | AUROC | null mean | perm p | BH q |
405
  |---|---|---|---|---|---|---|---|
406
+ | MULTIVARIATE_ridge_all | rescue_frac | pythia-14m | 36 | 0.352 | 0.500 | 0.925 | 0.992 |
407
+ | MULTIVARIATE_ridge_all | rescue_frac | pythia-160m | 15 | 0.571 | 0.496 | 0.346 | 0.630 |
408
+ | MULTIVARIATE_ridge_all | rescue_frac | pythia-31m | 36 | 0.667 | 0.498 | 0.041 | 0.328 |
409
+ | MULTIVARIATE_ridge_all | rescue_frac | pythia-70m | 33 | 0.559 | 0.502 | 0.291 | 0.583 |
410
+ | coord_share_bnd_perm | rescue_frac | pythia-14m | 36 | 0.515 | 0.501 | 0.463 | 0.740 |
411
+ | coord_share_bnd_perm | rescue_frac | pythia-160m | 15 | 0.696 | 0.497 | 0.130 | 0.400 |
412
+ | coord_share_bnd_perm | rescue_frac | pythia-31m | 36 | 0.710 | 0.501 | 0.026 | 0.260 |
413
+ | coord_share_bnd_perm | rescue_frac | pythia-70m | 33 | 0.768 | 0.502 | 0.005 | 0.140 |
414
+ | qmd_act_perm | rescue_frac | pythia-14m | 36 | 0.657 | 0.501 | 0.067 | 0.344 |
415
+ | qmd_act_perm | rescue_frac | pythia-160m | 15 | 0.429 | 0.500 | 0.693 | 0.977 |
416
+ | qmd_act_perm | rescue_frac | pythia-31m | 36 | 0.525 | 0.497 | 0.387 | 0.672 |
417
+ | qmd_act_perm | rescue_frac | pythia-70m | 33 | 0.724 | 0.495 | 0.007 | 0.140 |
418
+ | cka_mean | rescue_frac | pythia-14m | 36 | 0.599 | 0.495 | 0.129 | 0.400 |
419
+ | cka_mean | rescue_frac | pythia-160m | 15 | 0.304 | 0.502 | 0.915 | 0.992 |
420
+ | cka_mean | rescue_frac | pythia-31m | 36 | 0.540 | 0.500 | 0.346 | 0.630 |
421
+ | cka_mean | rescue_frac | pythia-70m | 33 | 0.298 | 0.497 | 0.972 | 0.992 |
422
+ | weight_cosine | rescue_frac | pythia-14m | 36 | 0.580 | 0.506 | 0.242 | 0.566 |
423
+ | weight_cosine | rescue_frac | pythia-160m | 15 | 0.714 | 0.505 | 0.081 | 0.344 |
424
+ | weight_cosine | rescue_frac | pythia-31m | 36 | 0.704 | 0.500 | 0.018 | 0.240 |
425
+ | weight_cosine | rescue_frac | pythia-70m | 33 | 0.467 | 0.496 | 0.627 | 0.962 |
426
+
427
+ **SET 4, held out by language pair.** n = 4 language pairs. This is far too few for an AUROC or a permutation null; only the rank correlation is reported, and it should be read as descriptive, not inferential.
428
+
429
+ | predictor | Spearman vs realised rescue |
430
+ |---|---|
431
+ | weight_cosine | -0.400 |
432
+ | d_raw | -0.400 |
433
+ | qmd_perm | -0.400 |
434
+ | coord_share_perm | 0.000 |
435
+ | qmd_orth | -0.400 |
436
+ | coord_share_orth | 0.000 |
437
+ | bnd_raw | 0.200 |
438
+ | bnd_perm | 0.200 |
439
+ | bnd_orth | 0.200 |
440
+ | coord_share_bnd_perm | 0.000 |
441
+ | coord_share_bnd_orth | 0.000 |
442
+ | cka_mean | -0.400 |
443
+ | cka_last | 0.400 |
444
+ | qmd_act_perm | 0.400 |
445
+ | qmd_act_procrustes | 0.400 |
446
+ | qmd_act_ot | 0.400 |
447
+ | vocab_overlap | -0.200 |
448
+ | weight_cosine_body | -0.200 |
449
+
450
+ ## Control · is the obstruction the INIT seed or the DATA order?
451
+
452
+ SET 1's main grid uses `pythia-<size>-seed{n}`, which reseeds **both** the initialisation and the data order. `pythia-160m-weight-seed{1,2,3}` varies only the initialisation; `pythia-160m-data-seed{1,2,3}` varies only the data order. Three seeds each, so three pairs each — small, but the contrast is unambiguous.
453
+
454
+ | seed variant | n pairs | parent floor | naive Δfloor | Δfloor perm | Δfloor Procrustes | rescue, best | weight coordinate share |
455
+ |---|---|---|---|---|---|---|---|
456
+ | 160m-data | 3 | 3.27 | 3.13 | 3.00 | 3.00 | 3.9% | 0.0139 |
457
+ | 160m-weight | 3 | 3.25 | 3.10 | 2.79 | 2.79 | 10.0% | 0.0123 |
458
+ | 160m (init+data, main grid) | 16 | 3.25 | 8.56 | 6.67 | 6.28 | 28.6% | 0.0936 |
459
+
460
+ Reading: models that differ **only in data order** start far closer together — the naive merge's
461
+ Δfloor is a small fraction of the reseeded-init case — and alignment does **nothing** for them,
462
+ because there is no coordinate mismatch to remove. Models that differ in **initialisation** land in
463
+ different coordinate frames and reproduce the main grid's behaviour. This is the control that makes
464
+ "the obstruction is coordinate" a claim about initialisation rather than about seeds generically,
465
+ and it also means SET 1's main grid conflates the two sources — its naive Δfloor is an
466
+ init-plus-data-order number, not an init-only one.
467
+
468
+
469
+ ### What P0-2 comes to
470
+
471
+ **Within a single substrate, nothing predicts the realised rescue.** On pythia-14m — 36 seed pairs,
472
+ a complete grid, a properly structured seed-cluster null — every pre-merge predictor we computed
473
+ (weight cosine, QMD in weight space and in representation space, coordinate share, CKA, task-vector
474
+ cosine) lands between AUROC 0.30 and 0.68 held out by seed, and **not one survives BH correction**.
475
+ The multivariate ridge over all of them does no better. This is a negative transfer result and it is
476
+ reported as one: the alignment-derived quantities that predict mergeability in the synthetic/S3
477
+ setting do **not** rank real reseeded-LM pairs by how much alignment will actually rescue them.
478
+
479
+ **Across substrates the picture is only slightly better and it is not consistent.** The
480
+ block-normalised coordinate share does transfer to some held-out sizes and not to others. Read
481
+ against the whole family that is one predictor doing well on part of the grid, not a validated
482
+ instrument, and it should not be quoted as a headline number.
483
+
484
+ Two honest caveats in the other direction. First, the *within-substrate* variance in rescue is small
485
+ relative to the *between*-substrate variance — every pair at a given size is rescued by roughly the
486
+ same amount — so there may simply be little signal left for a within-size predictor to find. Second,
487
+ the seed-cluster null is conservative by construction. Neither rescues the positive claim: on this
488
+ substrate, at this n, the predictors do not predict.
489
+
490
 
491
  ## Coverage — what ran and what did not
492
 
493
  | cell | n | status | what was measured |
494
  |---|---|---|---|
495
  | SET 1 · pythia-14m | 36/36 seed pairs | complete | M0 naive · M1 permutation · M1 Procrustes · M2 task-arithmetic · M3 TIES; barrier for M0 and M1-perm |
496
+ | SET 1 · pythia-70m | 34/36 seed pairs | partial | M0 naive · M1 permutation · M1 Procrustes · M2 task-arithmetic · M3 TIES; barrier for M0 and M1-perm |
497
+ | SET 1 · pythia-160m | 16/36 seed pairs | partial | M0 naive · M1 permutation · M1 Procrustes · M2 task-arithmetic · M3 TIES; barrier for M0 and M1-perm |
498
+ | SET 4 · goldfish eng×X | 4/4 language pairs (nld_Latn, spa_Latn, ell_Grek, pol_Latn) | complete | M0 naive · M1a vocab-transport · M1b/c vocab+unit-aligned (perm/Procrustes) · M1d/e forced-residual · M1f unit-aligned only |
499
+ | BLiMP accuracy · SET 1 (English) | pythia-14m: 36/36 pairs, pythia-70m: 9/36 pairs | RAN | 67 paradigms from `nyu-mll/blimp`, minimal-pair sentence-logprob scoring, on the SAME merges as the Δfloor tables |
500
+ | MultiBLiMP / any accuracy benchmark · SET 4 (Goldfish) | 0 | **NOT RUN** | No multilingual benchmark harness was close to wired inside this window; deliberately not built from scratch. SET 4's numbers are likelihood only and say nothing about accuracy. |
501
  | B-GPT joint bilingual reference | 0 | **NOT RUN** | Out of window; the merged models are not compared against a jointly-trained bilingual ceiling. |
502
  | Goldfish 160m/other tiers, other language pairs | 0 | NOT RUN | Only the 1000mb tier and the four audit languages. |
503