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Author SHA1 Message Date
logaritmiskandClaude Opus 5 076a7ded8c feat!: Gaussian's EP operations stop wearing arithmetic's clothes
`Gaussian` publicly implemented `Mul`, `Div`, `Add` and `Sub`. They were
the EP product, cavity and variance-space convolutions, and every one of
them lies to a reader who takes the operator at face value:

    a = N(10, 2)   b = N(4, 3)   c = N(1, 1)

    a * b        N(8.15, 1.66)   not 40
    a - b        sigma GREW, 2 -> sqrt(4 + 9)
    a * N(1, 0)  mu = NaN        "multiply by one"
    a / c        pi = -0.75      mu() prints a confident 0

The last is this crate's signature defect on a public operator. `Div` is
the cavity and can legitimately leave a negative precision, which is not
a distribution — and `mu()`/`sigma()` guard `pi <= 0` and report `0.0`
and `inf`, so it comes back as a plausible number with no panic, no
`Debug` marker and nothing to test against.

The four impls are now `pub(crate)` inherent methods that say what they
do: `ep_product`, `cavity`, `convolve`, `convolve_diff`, plus `scale`
for the one operation that genuinely is arithmetic. Nothing in a user's
workflow needed operator syntax; inference did, and it still has it.

`pi()` and `tau()` follow. Storing natural parameters is a performance
decision — it makes message passing two adds — not a contract. The
public surface is now exactly: `from_ms`, `from_mv`, `mu`, `sigma`,
`variance`, `probability_below`, `probability_above`. `from_mv` and
`variance` are promoted from `pub(crate)`; they are the honest pair for
callers who already hold a variance and should not pay a round trip
through the square root.

Four integration tests asserted bit-identity on `(pi, tau)`. They assert
it on `(mu, variance)` instead — still `assert_eq!`, still exact, and
`1/pi` and `tau/pi` are deterministic, so bit-equal natural parameters
give bit-equal moments. `a_nan_sigma_passes_through_from_ms` drops its
`|| g.pi().is_nan()` half: `sigma()` substitutes for `pi <= 0` and
`pi == inf`, so NaN survives to it only from a NaN precision.

`benches/gaussian.rs` is deleted. It timed two f64 additions through the
public operators, and keeping those public solely to feed it is the same
thing #73 objected to when a benchmark was dictating five public types.
The paths it covered are exercised by `batch` and `history_converge`
through the real call chain.

Closes #71.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_011hcFjNDmHXZF8URGLku5zZ
2026-09-09 23:13:10 +02:00
logaritmiskandClaude Opus 5 305f822964 fix: route the last three transcendentals through libm, and enforce it
CLAUDE.md requires transcendentals to go through libm rather than std,
because std delegates to the system math library and the two disagree by
one ULP often enough to change an iteration count in a fixed point.

Three production sites did not:

  factor/margin.rs:84  cavity.sigma().hypot(sigma)   12.136% of 1e6 inputs
  factor/margin.rs:92  f64::MIN_POSITIVE.ln()         3.437%
  factor/trunc.rs:98   f64::MIN_POSITIVE.ln()         same

`hypot` is the material one: it is on the path of every scored event, and
its divergence rate is HIGHER than the 9.7% the rule cites for `exp` as
its own justification. The two `ln` calls happen to agree bit-for-bit on
this host, which is exactly the platform dependence the rule exists to
remove.

The `hypot` choice itself was right and stays — the comment above it
explains why, and it is measured: naive sqrt(a^2 + b^2) overflows to inf
at 1e200 and flushes to zero at 1e-200 where hypot does neither. Only the
implementation moves.

tests/libm_rule.rs enforces it. The rule was stated plainly in CLAUDE.md
and still violated three times, so prose is evidently not sufficient. The
test strips `#[cfg(test)]` items by brace matching, plus comments and
string literals so prose is not mistaken for a call, then scans for std
method spellings. `sqrt` is exempt: IEEE 754 specifies it, so std and
libm cannot disagree.

Confirmed non-vacuous by reintroducing the `hypot` violation and watching
it fail with the offending line, then pass again on restore. Two further
tests pin the stripper itself, since a stripper that removed everything
would make the guard pass on anything.

Closes #63

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_011hcFjNDmHXZF8URGLku5zZ
2026-09-09 17:56:23 +02:00
logaritmiskandClaude Opus 5 633a503900 refactor!: remove the factor-graph surface nothing used, add try_winner
Two decisions taken before cutting 0.5.0.

#42 — the `Schedule` trait was public API the engine never called. Its
only call site was `Game::custom`, itself `#[doc(hidden)]`, and
`EpsilonOrMax` was never constructed anywhere. Removing that surface
showed the problem was larger than the issue described: with `custom`
gone, the compiler found `Factor`, `BuiltinFactor`, `RankDiffFactor` and
`TeamSumFactor` all dead too.

`Game::run_chain` drives a local `DiffFactor` enum and bypasses the
whole T1 abstraction — it has done since it was written. So this is not
just an unused extension point but the machinery it was built on, and
`CLAUDE.md` was documenting it as live architecture.

Removed: `graph` module, `Schedule`, `EpsilonOrMax`, `ScheduleReport`,
`Game::custom`, `Factor`, `BuiltinFactor`, `RankDiffFactor`,
`TeamSumFactor`. `TruncFactor`, `MarginFactor`, `VarStore` and `VarId`
stay — inference uses those. The measurement behind choosing removal
over wiring is in #42: the within-game loop converges in 1 to 8
iterations against a cap of 30, so a `Residual` schedule has no headroom
to reclaim, and `Damped` already shipped as `ConvergenceOptions::alpha`.

#20 — `Outcome::winner` panicking on an out-of-range index. Kept, and
the reasoning is now on the method. It is the only constructor here that
validates, which looks inconsistent until you try deferring like its
siblings: `winner(5, 2)` produces ranks `[1, 1]`, an all-tied draw that
ingestion accepts without complaint when `p_draw > 0`. Asking "team 5
won" and silently getting "everyone drew" is the exact failure this
crate keeps removing, so the check belongs where the mistake is.

Adds `Outcome::try_winner` for indices that are computed or parsed
rather than written literally, following the `new`/`try_new` convention.
That is additive; the panicking form stays because every call site in
this repo, its tests and its README passes literals, where a `?` would
be noise.

BREAKING CHANGE: the `graph` module and everything it exported are
removed, as are `Game::custom` and `ScheduleReport`.

Closes #42. Closes #20.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_011hcFjNDmHXZF8URGLku5zZ
2026-09-08 02:14:43 +02:00
logaritmiskandClaude Opus 5 17d072b2ae fix: route every transcendental through libm, and combine sigmas with hypot
Follow-on from #41, which added `libm` for `erfc`. Surveying what else
the dependency offers: its unique surface over `std` is `erf`/`erfc`,
`lgamma`/`tgamma` and Bessel functions, and only the first was ever
needed. But the survey found something better than another special
function.

`std`'s `exp` and `ln` delegate to the *system* math library. IEEE 754
specifies the basic operations and `sqrt` exactly and says nothing about
transcendentals, so those differ per platform. Measured here over 200k
inputs:

    exp: 19425/200000 differ from libm (worst 1 ulp)
    log:  9932/200000 differ

Inference is an iterative fixed point, so a one-ULP difference can change
an iteration count and move the answer by more than one ULP. Routing
every transcendental through `libm` makes a fit reproducible across
platforms — a stronger guarantee than `tests/determinism.rs`, which only
covers thread counts.

It costs nothing. `Batch::iteration` measured -2.7% [-5.7%, -0.3%] with
the whole set swapped, and not one golden moved.

Also switches the two places that combined sigmas as
`sqrt(a^2 + b^2)` to `hypot`. Squaring overflows to infinity above
~1.3e154 and flushes to zero below ~1.5e-154 — measured, the naive form
returns `inf` where `hypot` returns 1.41e160 — and `Gaussian`'s
constructors are public, so a caller can reach both ends.

Deliberately not done: rewriting the KL divergence's `ln` of a ratio via
`ln_1p`. The cancellation is real as the ratio approaches one, but
measured absolute error is at most ~1e-11 in a quantity of order 0.4
nats, so it changes nothing.

The invariant is recorded in `CLAUDE.md` and on `erfc`'s own docs, since
nothing enforces it mechanically.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_011hcFjNDmHXZF8URGLku5zZ
2026-09-07 22:33:30 +02:00
logaritmiskandClaude Opus 5 683813ec10 fix: correct erfc_inv's sign error and keep evidence in log space
A systematic scan for precision defects, following the tail-precision
work in 7341669. Three findings; the first is a correctness bug in a
released version.

1. `erfc_inv`'s initial guess had the wrong sign. Numerical Recipes'
   `inverfc` uses -0.70711 as the leading coefficient; this used
   +FRAC_1_SQRT_2. Since `rational - t` is negative, that put Newton on
   the mirror image of the root, and three fixed iterations could not
   cross back. Measured against exact standard-normal quantiles:

       p_draw   old rel err   new rel err
       0.50        1.46e-7       8.40e-8
       0.90        1.02e-1       8.63e-9
       0.95        3.06e-1       1.91e-8
       0.99        8.05e-1       5.89e-9

   `compute_margin` inherited it, so the draw margin was wrong for any
   `p_draw` above about 0.6 and *non-monotone* above 0.9 — it ran
   0.674, 1.476, 0.503, 0.982 as p_draw went 0.5, 0.9, 0.99, 0.999. A
   history configured for a 0.99 draw rate was being fitted at 0.385.
   Note it was slightly wrong everywhere, not only in the tail.

2. `MarginFactor` computed a density and clamped it. `pdf` underflows
   past ~38 sigma, so `ln` of the clamped zero reported -708 nats
   however far out the score actually was: 4292 nats adrift at 100
   sigma, and unbounded beyond. This is the same defect as the one
   fixed in `TruncFactor`, one file over, on the scored-outcome path.

3. `TruncFactor` still bottomed out past ~38 sigma even after 7341669
   removed the cancellation, because the linear probability itself
   underflows there.

2 and 3 are fixed the same way: factors cache a *log* evidence, built
from new `ln_pdf`, `ln_sf` and `ln_interval` helpers that factor the
shared exponential out analytically via the `erfcx` added earlier.
Nothing underflows, at any separation.

One golden moved. `test_1vs1vs1` runs at `p_draw = 0.5`, so it goes
through `compute_margin`; its 1e-6-place values shifted. Verified as
movement *toward* analytic truth by comparing both the old and new
inverse against exact quantiles, per the goldens policy in CLAUDE.md —
not re-baselined on faith.

Two test tolerances are asserted at 1e-6 rather than tighter because
above x = 2 `erfcx` uses a continued fraction accurate to ~1e-15 while
`erfc` carries ~1e-7, so the log path is the more accurate of the two
and they part company at `erfc`'s error. That floor is tracked in #41.

Refs #41

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_011hcFjNDmHXZF8URGLku5zZ
2026-09-07 21:45:03 +02:00
logaritmiskandClaude Opus 5 9b2c2b38c8 docs: complete the public API documentation contract
Closes the last open item in #25. `cargo clippy -W missing_errors_doc
-W missing_panics_doc -W must_use_candidate -W doc_markdown` went from 56
warnings to zero.

The 13 hand-written sections name the actual variants each function returns
rather than gesturing at "an error". Establishing that meant reading the error
paths — `Game::ranked` alone returns four distinct variants, and `record_draw`
can hit TieWithoutDrawProbability where `record_winner` provably cannot, since
a two-team decisive outcome has nothing to tie. Documenting those as
interchangeable would have been worse than leaving them undocumented, because
a reader would trust it.

Two existing doc comments already described panics in prose but not under a
`# Panics` heading, so neither rustdoc nor clippy surfaced them:
`Outcome::winner` and `EventBuilder::weights`. Both now carry the heading, and
`Outcome::winner` gained the note that it ties every loser, so `n >= 3` needs a
positive p_draw — the crate's easiest error to hit by accident.

The 43 mechanical fixes (31 `#[must_use]` on pure accessors, 11 missing
backticks) were applied with `cargo clippy --fix`. `#[must_use]` on Gaussian's
arithmetic and on `posteriors()` matters: discarding those results is always a
bug, and until now nothing said so.

Also documented why `[profile.release] debug = true` exists — cargo-flamegraph
needs the symbols, and library profile settings are ignored downstream, so it
reads as an oversight without the note.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01T5SYDExxL4vZgvunrcNSMc
2026-08-27 17:43:31 +02:00
logaritmiskandClaude Opus 5 0f1a1b8911 fix(evidence): accumulate in log space and floor the per-link value
Per-link evidence was multiplied in linear space and logged only at the
end. Each link contributes a probability in (0, 1], so the product over an
n-team game decays geometrically: around a thousand links it flushes to
exactly 0.0 and `ln(0.0)` is `-inf`, which then propagates through the sum
in `History::log_evidence_internal` and takes the whole history with it.
`Game::free_for_all` builds one team per player, so this is reachable at
the competitor counts the T3 benchmarks target.

`Game`, `OwnedGame`, and `time_slice::Event` now carry `log_evidence`
directly, summed over links rather than multiplied then logged.

The cached per-link evidence is also floored at `f64::MIN_POSITIVE`. It
could legitimately reach zero or go negative: `1.0 - cdf(..)` rounds to
zero for a near-certain outcome, and the `erfc` approximation carries
~1e-7 error so `cdf` can exceed 1.0 and make the difference negative —
`ln` of which is NaN.

Existing log-evidence goldens are unchanged, confirming the accumulation
is numerically equivalent in the range where the old form worked.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01DnsaJg74eNSva3PJjK2eej
2026-08-04 21:43:57 +02:00
logaritmisk aacaa60baa feat(factor): add MarginFactor::propagate_with_alpha for EP damping
Mirrors TruncFactor: inherent damped-propagate method, trait impl
delegates with α=1.0. Existing goldens unchanged because cavity*new_msg
equals the previous marginal write when α=1.0.
2026-05-08 15:03:45 +02:00
logaritmiskandClaude Opus 4.7 8b53cacd64 T4 (MarginFactor): scored outcomes via Gaussian-margin EP evidence
Adds soft Gaussian-observation evidence on the per-pair diff variable,
enabling continuous score margins as a richer alternative to ranks.

Public API:
- `Outcome::Scored([scores])` (non-breaking enum extension under
  `#[non_exhaustive]`).
- `Game::scored(teams, outcome, options)` constructor parallel to
  `Game::ranked`.
- `EventBuilder::scores([...])` fluent helper.
- `HistoryBuilder::score_sigma(σ)` knob (default 1.0, validated > 0).
- `GameOptions::score_sigma`.
- `EventKind` re-exported from `lib.rs` (annotated `#[non_exhaustive]`).
- New `InferenceError::InvalidParameter { name, value }` variant.

Internals:
- `MarginFactor` (`factor/margin.rs`): Gaussian observation factor that
  closes in one EP step; cavity-cached log-evidence mirrors `TruncFactor`.
- `BuiltinFactor::Margin` dispatch arm.
- `DiffFactor` enum in `game.rs` lets `Game::likelihoods` and the new
  `likelihoods_scored` share the per-pair link abstraction.
- Per-event `EventKind { Ranked, Scored { score_sigma } }` routed through
  `TimeSlice::add_events`, `iteration_direct`, and `log_evidence`.

Tests: 88 lib + 27 integration (4 new in `tests/scored.rs`); existing
goldens byte-identical.  Bench: `benches/scored.rs` baseline ~960µs for
60 events × 20-player pool with default convergence.

Plan: docs/superpowers/plans/2026-04-27-t4-margin-factor.md
Spec item marked Done.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
2026-04-27 08:47:36 +02:00