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esh-pfi-infrastructure/docs/pfi
vh 5171f19e16 docs(erp-dpo): the PIPPA length clip, measured — DPO pairs would inherit it
The run-2 gate found tuned rp turns 36% shorter than base. brokkr hypothesised
the mix was teaching PIPPA's 2023 Character.AI product clip; the corpus side is
now measured and confirmed. PIPPA's max is 123 words EXACTLY, 100% at or under
it, and 0.00% in the 124-130 band -- a wall, not a preference. Every other root
crosses its own p99 smoothly.

The mechanism is sharper than 'PIPPA is in the mix'. PIPPA is 70.3% of bot TURNS
but only 37.5% of bot WORDS, precisely because its turns are clipped -- and
length is learned per turn, not per token. By loss tokens it looks like a third
of the dialogue signal; by end-of-turn demonstrations it is seven in ten from a
source that cannot exceed 123 words. Generalises: a length-clipped root is
over-represented in the length signal by exactly the ratio its clipping creates.

Counter-evidence recorded too: the tune landed near PIPPA's MEDIAN (67), not its
CAP, which is central tendency rather than learning the boundary. Weaker claim
than the hypothesis, and not demonstrated either way.

Filed here rather than only in the gate record because preference pairs
generated FROM this tune inherit its length distribution in both chosen and
rejected -- DPO would train an artifact in as an explicit objective. Settle the
length question before generating pairs.
2026-08-26 02:25:08 -07:00
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