docs/FSOT_FLUENCY_GAP.md

FSOT fluency gap solver — compete via mathematics of densify

Built: 2026-07-21T18:27:20.793197+00:00

Law (fixed — not fitted to BLEU)

• Formula: S=K(T1+T2+T3) pin D1D38A
• Linguistic panel: S=0.651324761885 T1=0.549955 T2=1.000000 T3=1.707063e-17
• Densify students cannot rewrite K or seeds.

Surface mapping (competitiveness as FSOT-shaped S)

Component	Surface meaning	Metric drivers
T1_surf	Lexicon / morph base	coverage × U-F1
T2_surf	Linear phrase map	BLEU-1 × bigram retention
T3_surf	Order / fluency valve	BP × chrF
S_surf	K·(T1+T2+T3)	staged competitor bar

Staged bar S_surf ≈ 0.72008 (T1=0.650 T2=0.650 T3=0.414)

Before → after densify

Metric	Before	After	Δ
BLEU-4	2.2	18.82	16.62
BLEU-1	45.87	86.86	40.99
U-F1	34.81	77.78	42.97
chrF	25.07	61.47	36.4
Coverage	91.3	100.0	—

Densify inject: +0 unigrams, +0 bigrams/templates (product path).

Per-lang priority (ΔS densify budget)

Lang	ΔS	Priority	Budget	B1 after	BLEU after
zh	0.6562	T1	1.2848	100.0	12.15
ja	0.6457	T1	1.2642	99.61	10.82
ko	0.4289	T2	0.8397	95.88	28.47
hi	0.3787	T2	0.7414	42.79	3.78
tr	0.3688	T2	0.7221	95.2	22.16
ar	0.3533	T2	0.6917	92.49	26.81
de	0.3389	T2	0.6636	81.11	17.05
he	0.3116	T2	0.6101	96.37	23.88
ru	0.3014	T2	0.5900	93.09	21.08
la	0.3010	T2	0.5894	97.5	22.15
fr	0.2944	T2	0.5764	79.65	14.62
pl	0.2858	T2	0.5596	95.44	20.2
es	0.2517	T2	0.4927	80.74	16.25
nl	0.2341	T2	0.4583	81.63	20.99
pt	0.2165	T2	0.4238	81.65	16.79
it	0.2139	T2	0.4188	85.41	21.96

How this is solving toward competitiveness

1. Measure gap as ΔS_surf, not ad-hoc loss.
2. Allocate densify by component shortfall (T1/T2/T3) × archive growth.
3. T3-priority langs get phrase templates + light EN reorder valve.
4. Law S stays the constitution for converse/cert; fluency is student densify.

Staged bars are intermediate (BLEU-4≈20, B1≈65), not final Google/DeepL SOTA. Solving ΔS_surf with densify raises surface fluency; law S unchanged.

Next FSOT-native levers

• Raise staged bar toward neural (BLEU-4 30+) once T2/T3 densify saturates
• NLLB teacher densify for T2 (still student)
• FLORES eval when Hub access accepted
• Optional neural student under cert gate — densify only