two more places for similarity: points='shape' (WHICH triple the model uses, argmin |phi-xi| over declared candidates — select, never weight) and direction='dissimilar' (the far end read by |f| rather than by distance); defaults bit-identical, P1-P5 pinned (7 green), inertness counters make an inert mode a failed EXPERIMENT rather than a pass; each grid writes to its own file

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

PREREG_points_and_direction_2026-09-21.md

@@ -0,0 +1,87 @@
+# PREREG — похожесть в двух ещё незанятых местах: СОСТАВ ТОЧЕК и НАПРАВЛЕНИЕ
+
+Составлено до реализации. Основание — `FINDINGS_slope_gate.md`: решает **валюта и место** чтения
+похожести. Одна и та же идея «отказывайся до шага» дала 4449 вызовов на APS при отказе по прогрессу
+скобки и 2848 при отказе по форме модели — разница 1601 вызов. Карта мест решения показала два
+незанятых:
+
+| место | чем решается сейчас |
+|---|---|
+| **состав точек для модели** | **давностью**: `x_prev2 ← x_prev ← x ← x_new`, всегда три последних |
+| **направление** (какой конец «дальний») | **расстоянием**: `far = B if \|B−x\| ≥ \|A−x\| else A` |
+
+---
+
+## 1. Режим A — состав точек по ФОРМЕ (`points="shape"`)
+
+Оценка наклона строится на тройке точек. Сейчас тройка берётся по давности, даже если она
+плохо обусловлена. Brent, TOMS 748 и Chandrupatla все **управляют составом точек** — это часть их
+конструкции, а у нас этого места нет вовсе.
+
+**Признак — та же валюта, что уже сработала: форма конфигурации, безразмерно.** Для тройки
+`(x, u, v)` считаются два отношения в духе Chandrupatla:
+
+    ξ = (x − u)/(v − u)      — отношение ПОЗИЦИЙ
+    φ = (f(x) − f(u))/(f(v) − f(u))   — отношение ЗНАЧЕНИЙ
+
+Для линейной `f` выполняется `φ = ξ` точно, поэтому `|φ − ξ|` — безразмерная мера непохожести
+конфигурации на линейную. Правило: **argmin |φ − ξ|** по объявленному списку кандидатов.
+
+**Список кандидатов объявляется здесь и не расширяется по результату:**
+
+    T1 = (x, x_prev, x_prev2)   — нынешнее правило давности
+    T2 = (x, x_prev, far)       — свежая точка плюс дальний конец скобки
+    T3 = (x, A, B)              — оба конца доказанной скобки
+
+Вырожденные (совпадающие абсциссы или значения) выбрасываются. Порога нет: это **argmin по
+имеющимся вариантам**, а не сравнение с числом. Правило корпуса «select, never weight» соблюдено —
+тройка **выбирается**, оценки не взвешиваются.
+
+## 2. Режим B — направление по НЕПОХОЖЕСТИ (`direction="dissimilar"`)
+
+Сейчас «дальний» конец — геометрически более удалённый. Похожесть даёт другой ответ: дальним считать
+конец, чьё `|f|` **больше**, то есть менее похожее на ноль. Ни константы, ни порога — сравнение двух
+имеющихся величин.
+
+**Режимы независимы и мерятся отдельно** (правило «менять одно за раз»); комбинация A+B мерится
+третьим прогоном только если оба по отдельности не ухудшили APS.
+
+## 3. Цели
+
+Точка отсчёта — уже достигнутое гейтом на наклоне (`slope.ratio.derived3.project`):
+APS **2848**, CHA **3074**, два набора **5922**, 193/199, `over2x = 0`.
+
+| величина | цель |
+|---|---|
+| APS-154 | **≤ 2848** (не хуже текущего; идеально — вернуть 2806) |
+| CHA-45 | **≤ 2857** (недобранная цель ITP; сейчас 2903 по-наборно) |
+| два набора | **< 5922** |
+| решено | ≥ 193/199 |
+| гарантия `2⌈log₂(w/xtol)⌉+3` | `over2x = 0` |
+
+## 4. Предсказания и фальсификаторы
+
+| # | Предсказание | ФАЛЬСИФИКАТОР → вывод |
+|---|---|---|
+| **A1** | режим A не ухудшает APS (≤2848) и улучшает CHA (<2903) | ухудшает APS → состав точек не то место, режим отвергается |
+| **A2** | выбор тройки **не инертен**: отличается от давностной в ≥5 % шагов | <1 % → режим ничего не меняет, замер НЕ является свидетельством ни за, ни против |
+| **B1** | режим B не ухудшает APS (≤2848) | ухудшает → направление по непохожести отвергается |
+| **B2** | выбор конца отличается от геометрического в ≥5 % шагов | <1 % → инертен, замер пуст |
+| **C** | гарантия цела в обоих режимах | нарушена → немедленное закрытие режима |
+
+**Правило остановки:** APS ухудшился или гарантия нарушена ⇒ режим не принимается. Инертность (A2/B2)
+⇒ результат не толкуется как подтверждение: это отсутствие эксперимента, а не его исход.
+
+## 5. Гейты реализации (тесты ДО рейтинга)
+
+| # | Условие | Проверка |
+|---|---|---|
+| **P1** | `points="recent"` и `direction="distance"` дают побитово прежний результат | равенство кортежей на наборе задач и сторожей |
+| **P2** | в обоих признаках нет констант | греп по коду (без комментариев): только `0.0`, `0.5`, `1.0` |
+| **P3** | счётчики `stats['triple_changed']`, `stats['dir_changed']` считают неинертность | тест на обоих |
+| **P4** | вырожденные тройки отбрасываются, а не дают деление на ноль | тест на совпадающих абсциссах и значениях |
+| **P5** | ни один режим не добавляет вызовов `f` | число вызовов ≤ число шагов + 2 |
+
+**Дисциплина:** аудит после правки и до запуска; смоук ×2 локально; свипы в свои файлы
+(`sweep_points.json`, `sweep_direction.json`), `sweep_full.json` не трогать; числа только с Linux;
+замороженные копии; числа показываются немедленно.

simroot/pure.py

@@ -121,6 +121,47 @@ GUARDS = ("none", "bracket", "step", "both", "project", "safe", "credit")
 SPACES = ("x", "log")
 
 
+POINT_RULES = ("recent", "shape")
+DIRECTIONS = ("distance", "dissimilar")
+
+
+def _shape_defect(x, fx, u, fu, v, fv):
+    """|phi - xi| for the triple, or None when it is degenerate.
+
+    xi = (x - u)/(v - u) is a ratio of POSITIONS, phi = (fx - fu)/(fv - fu) a ratio of
+    VALUES; both are invariant under affine rescaling of x and of f. For a linear f they
+    are equal, so their gap measures how unlike a linear configuration the triple is —
+    the same dimensionless currency Chandrupatla's acceptance band is written in."""
+    if v == u or fv == fu:
+        return None
+    xi = (x - u) / (v - u)
+    ph = (fx - fu) / (fv - fu)
+    if not (math.isfinite(xi) and math.isfinite(ph)):
+        return None
+    return abs(ph - xi)
+
+
+def _pick_triple(x, fx, x_prev, f_prev, x_prev2, f_prev2, A, FA, B, FB, far):
+    """SELECT the triple whose configuration is least unlike a linear one (PREREG
+    2026-09-21, mode A). Candidates are declared, not searched: the recency triple, the
+    recent point with the far bracket end, and the two proven bracket ends. Returns
+    ((xu, fu), (xv, fv)) or None when nothing is admissible."""
+    far_f = FB if far == B else FA
+    cands = (((x_prev, f_prev), (x_prev2, f_prev2)),
+             ((x_prev, f_prev), (far, far_f)),
+             ((A, FA), (B, FB)))
+    best, best_d = None, None
+    for u, v in cands:
+        if u[0] is None or v[0] is None:
+            continue
+        d = _shape_defect(x, fx, u[0], u[1], v[0], v[1])
+        if d is None or x == u[0] or x == v[0]:
+            continue
+        if best_d is None or d < best_d:
+            best, best_d = (u, v), d
+    return best
+
+
 def _log_map(t, c, s):
     """u = sign(t - c) * log1p(|t - c| / s).  An ADDITIVE step in u is a
     MULTIPLICATIVE step in x, which is what the wide-bracket families need: the
@@ -413,7 +454,8 @@ def _local_order(x2, f2, x1, f1, x0, f0):
 
 def pure_root(f, a, b, xtol, maxfev, similarity="ratio", scale="derived",
               guard="step", stats=None, budget_factor=2.0,
-              budget_extra=None, endowment=1.0, space="x", prestep="none"):
+              budget_extra=None, endowment=1.0, space="x", prestep="none",
+              points="recent", direction="distance"):
     """The pure similarity root finder.
 
     similarity : key into PURE_SIMS
@@ -469,6 +511,14 @@ def pure_root(f, a, b, xtol, maxfev, similarity="ratio", scale="derived",
         raise ValueError(f"unknown space {space!r}")
     if prestep not in ("none", "progress", "slope"):
         raise ValueError(f"unknown prestep {prestep!r}")
+    if points not in POINT_RULES:
+        raise ValueError(f"unknown points rule {points!r}")
+    if direction not in DIRECTIONS:
+        raise ValueError(f"unknown direction {direction!r}")
+    if points == "shape" and scale not in ("derived3", "derived3_rho", "derived3_m"):
+        # the triple only exists for the three-point scale; selecting one under a
+        # two-point scale would change nothing and hide that
+        raise ValueError("points='shape' requires a three-point scale (derived3*)")
     if prestep == "slope" and scale not in ("derived", "derived3"):
         # there is no slope to judge under a chosen or bracket scale; judging something
         # else would hide that, so the call fails instead
@@ -501,11 +551,15 @@ def pure_root(f, a, b, xtol, maxfev, similarity="ratio", scale="derived",
         sg.credit = endowment
         forced = 0
         pre_refused = 0
+        triple_changed = 0
+        dir_changed = 0
         slope = 0.0
         slope_prev = None
         if stats is not None:
             stats['forced'] = 0
             stats['pre_refused'] = 0
+            stats['triple_changed'] = 0
+            stats['dir_changed'] = 0
 
         while abs(B - A) > xtol:
             if sg.bisect_before_step(abs(B - A)):
@@ -516,11 +570,38 @@ def pure_root(f, a, b, xtol, maxfev, similarity="ratio", scale="derived",
                 sg.note_step(x_new - x)
             else:
                 far = B if abs(B - x) >= abs(A - x) else A
+                if direction == "dissimilar":
+                    # PREREG 2026-09-21, mode B: the far end read by SIMILARITY instead of
+                    # geometry — the end whose |f| is larger is the one LESS similar to zero,
+                    # i.e. the one the root is further from.  Two values already in hand are
+                    # compared; no constant.
+                    far_sim = B if abs(FB) >= abs(FA) else A
+                    if far_sim != far:
+                        dir_changed += 1
+                    far = far_sim
                 if scale in ("derived", "derived_rho"):
                     slope = ((fx - f_prev) / (x - x_prev)) if x != x_prev else 0.0
                     sc = abs(slope) * abs(far - x)
                 elif scale in ("derived3", "derived3_rho", "derived3_m"):
-                    slope = _slope3(x, fx, x_prev, f_prev, x_prev2, f_prev2)
+                    if points == "shape":
+                        # PREREG 2026-09-21, mode A: which THREE points the model is built
+                        # on, chosen by the SHAPE of the configuration instead of by recency.
+                        # For a linear f the position ratio and the value ratio coincide, so
+                        # |phi - xi| is a dimensionless measure of how unlike a linear
+                        # configuration a triple is; the triple minimising it is SELECTED
+                        # (the corpus rule is select, never weight).  argmin over the declared
+                        # candidates needs no threshold.
+                        pick = _pick_triple(x, fx, x_prev, f_prev, x_prev2, f_prev2,
+                                            A, FA, B, FB, far)
+                        if pick is None:
+                            slope = _slope3(x, fx, x_prev, f_prev, x_prev2, f_prev2)
+                        else:
+                            (xu, fu), (xv, fv) = pick
+                            if xu != x_prev or xv != x_prev2:
+                                triple_changed += 1
+                            slope = _slope3(x, fx, xu, fu, xv, fv)
+                    else:
+                        slope = _slope3(x, fx, x_prev, f_prev, x_prev2, f_prev2)
                     sc = abs(slope) * abs(far - x)
                     if scale == "derived3_m":
                         # REFUTED as an improvement - kept for reproducibility.
@@ -665,7 +746,7 @@ def pure_root(f, a, b, xtol, maxfev, similarity="ratio", scale="derived",
                 if x_new == x or x_new == x_prev:
                     # the bracket can no longer be split in floating point
                     if stats is not None:
-                        stats['forced'] = forced; stats['pre_refused'] = pre_refused
+                        stats['forced'] = forced; stats['pre_refused'] = pre_refused; stats['triple_changed'] = triple_changed; stats['dir_changed'] = dir_changed
                     return x_new, g.n, abs(B - A) <= xtol
 
             w_before = abs(B - A)
@@ -677,7 +758,7 @@ def pure_root(f, a, b, xtol, maxfev, similarity="ratio", scale="derived",
             x, fx = x_new, fnew
             if fnew == 0.0:
                 if stats is not None:
-                    stats['forced'] = forced; stats['pre_refused'] = pre_refused
+                    stats['forced'] = forced; stats['pre_refused'] = pre_refused; stats['triple_changed'] = triple_changed; stats['dir_changed'] = dir_changed
                 return x_new, g.n, True
             if FA * fnew < 0.0:
                 B, FB = x_new, fnew
@@ -686,9 +767,9 @@ def pure_root(f, a, b, xtol, maxfev, similarity="ratio", scale="derived",
             if guard == "credit":
                 sg.note_shrink(w_before, abs(B - A))
         if stats is not None:
-            stats['forced'] = forced; stats['pre_refused'] = pre_refused
+            stats['forced'] = forced; stats['pre_refused'] = pre_refused; stats['triple_changed'] = triple_changed; stats['dir_changed'] = dir_changed
         return 0.5 * (A + B), g.n, True
     except _Budget:
         if stats is not None:
-            stats['forced'] = forced; stats['pre_refused'] = pre_refused
+            stats['forced'] = forced; stats['pre_refused'] = pre_refused; stats['triple_changed'] = triple_changed; stats['dir_changed'] = dir_changed
         return x, g.n, False

sweep_full.py

@@ -111,10 +111,13 @@ def make_method(spec):
     sim, scale, guard = spec[1], spec[2], spec[3]
     space = spec[4] if len(spec) > 4 else "x"
     prestep = spec[5] if len(spec) > 5 else "none"
+    points = spec[6] if len(spec) > 6 else "recent"
+    direction = spec[7] if len(spec) > 7 else "distance"
 
     def m(f, a, b, xtol, maxfev):
         return pure_root(f, a, b, xtol, maxfev, similarity=sim,
-                         scale=scale, guard=guard, space=space, prestep=prestep)
+                         scale=scale, guard=guard, space=space, prestep=prestep,
+                         points=points, direction=direction)
     return m
 
 
@@ -124,6 +127,10 @@ def label(spec):
     tag = "pure"
     if len(spec) > 4 and spec[4] != "x":
         tag = spec[4]
+    if len(spec) > 6 and spec[6] != "recent":
+        tag = f"{tag}+shape"
+    if len(spec) > 7 and spec[7] != "distance":
+        tag = f"{tag}+dissim"
     if len(spec) > 5 and spec[5] != "none":
         # name the gate by WHICH gate it is: "progress" is a measured negative and must
         # never be confused with "slope" in a results file
@@ -191,6 +198,23 @@ def build_grid_log(smoke):
             for sim in sims for sc in ("derived", "derived3") for gu in guards]
 
 
+def build_grid_points(smoke):
+    """Mode A (PREREG 2026-09-21): the triple chosen by shape, on top of the slope gate that
+    already reached the project target. Three-point scale only — a triple must exist."""
+    sims = ["ratio", "sqrt"] if smoke else sorted(PURE_SIMS)
+    guards = ("credit", "project") if smoke else GUARD_MODES
+    return [("pure", sim, "derived3", gu, "x", "slope", "shape", "distance")
+            for sim in sims for gu in guards]
+
+
+def build_grid_direction(smoke):
+    """Mode B (PREREG 2026-09-21): the far end read by dissimilarity, on top of the slope gate."""
+    sims = ["ratio", "sqrt"] if smoke else sorted(PURE_SIMS)
+    guards = ("credit", "project") if smoke else GUARD_MODES
+    return [("pure", sim, sc, gu, "x", "slope", "recent", "dissimilar")
+            for sim in sims for sc in ("derived", "derived3") for gu in guards]
+
+
 def build_grid_slope(smoke):
     """The slope-stability gate grid (PREREG 2026-09-21). Only derived scales: there must be
     a slope to judge. Baselines are not recomputed — they are in sweep_full.json."""
@@ -231,7 +255,11 @@ def main():
     logmode = "--log" in sys.argv          # the u-space grid, written to its OWN file
     gatemode = "--gate" in sys.argv        # the pre-step gate grid, likewise
     slopemode = "--slope" in sys.argv      # the slope-stability gate grid
-    specs = (build_grid_slope(smoke) if slopemode else
+    pointsmode = "--points" in sys.argv    # mode A: triple by shape
+    dirmode = "--direction" in sys.argv    # mode B: far end by dissimilarity
+    specs = (build_grid_points(smoke) if pointsmode else
+             build_grid_direction(smoke) if dirmode else
+             build_grid_slope(smoke) if slopemode else
              build_grid_gate(smoke) if gatemode else
              build_grid_log(smoke) if logmode else build_grid(smoke))
     t0 = time.time()
@@ -249,6 +277,14 @@ def main():
 
     # the published sweep_full.json is what verify_article.py checks the paper
     # against, so the log grid never writes into it
+    if pointsmode or dirmode:
+        base = "sweep_points" if pointsmode else "sweep_direction"
+        out = f"{base}_smoke.json" if smoke else f"{base}.json"
+        with open(out, "w", encoding="utf8") as fh:
+            json.dump(results, fh)
+        print(f"wrote {out}  ({time.time() - t0:.0f}s total)", flush=True)
+        report(results)
+        return
     if slopemode:
         out = "sweep_slope_smoke.json" if smoke else "sweep_slope.json"
         with open(out, "w", encoding="utf8") as fh:

tests/test_points_direction.py

@@ -0,0 +1,106 @@
+"""Gates P1-P5 for the two new places similarity is read (PREREG_points_and_direction_2026-09-21).
+
+mode A  points="shape"       — WHICH three points the model is built on, chosen by the shape
+                               of the configuration (argmin |phi - xi|) instead of by recency
+mode B  direction="dissimilar" — WHICH end is "far", read as the end whose |f| is larger
+                               (less similar to zero) instead of the geometrically distant one
+
+Inertness is a declared failure of the EXPERIMENT, not a pass: if a mode changes nothing, its
+numbers are not evidence either way, so the counters are pinned here.
+"""
+
+from __future__ import annotations
+
+import inspect
+import math
+import re
+
+import pytest
+
+from simroot import pure as P
+
+SMOOTH = [
+    (lambda t: t ** 3 - 2.0 * t - 5.0, 2.0, 3.0),
+    (lambda t: math.exp(t) - 5.0, 0.0, 3.0),
+    (lambda t: t ** 2 - 2.0, 0.5, 2.0),
+    (lambda t: math.cos(t) - t, 0.0, 1.0),
+    (lambda t: t ** 3 - t + 0.2, -2.0, 2.0),
+]
+
+
+def test_P1_defaults_are_bit_identical_to_the_published_path():
+    for f, a, b in SMOOTH:
+        for guard in ("credit", "project", "safe", "step"):
+            base = P.pure_root(f, a, b, 1e-12, 300, similarity="ratio",
+                               scale="derived3", guard=guard)
+            same = P.pure_root(f, a, b, 1e-12, 300, similarity="ratio", scale="derived3",
+                               guard=guard, points="recent", direction="distance")
+            assert base == same, (guard, base, same)
+
+
+def test_P2_neither_rule_carries_a_constant():
+    src = inspect.getsource(P._pick_triple) + inspect.getsource(P._shape_defect)
+    code = "\n".join(line.split("#", 1)[0] for line in src.splitlines())
+    literals = set(re.findall(r"(?<![\w.])\d+\.\d+(?![\w.])", code))
+    assert literals == set(), f"constants in the triple rule: {literals}"
+    body = inspect.getsource(P.pure_root)
+    start = body.index('if direction == "dissimilar":')
+    end = body.index('if scale in ("derived", "derived_rho")', start)
+    dcode = "\n".join(line.split("#", 1)[0] for line in body[start:end].splitlines())
+    assert set(re.findall(r"(?<![\w.])\d+\.\d+(?![\w.])", dcode)) == set()
+
+
+def test_P3_the_counters_report_whether_a_mode_is_inert():
+    changed = 0
+    for f, a, b in SMOOTH:
+        st = {}
+        _x, _n, ok = P.pure_root(f, a, b, 1e-12, 300, similarity="ratio", scale="derived3",
+                                 guard="credit", points="shape", stats=st)
+        assert ok and "triple_changed" in st
+        changed += st["triple_changed"]
+    assert changed >= 1, "mode A never changed the triple on any probe problem — inert"
+
+    dchanged = 0
+    for f, a, b in SMOOTH:
+        st = {}
+        _x, _n, ok = P.pure_root(f, a, b, 1e-12, 300, similarity="ratio", scale="derived3",
+                                 guard="credit", direction="dissimilar", stats=st)
+        assert ok and "dir_changed" in st
+        dchanged += st["dir_changed"]
+    assert dchanged >= 1, "mode B never changed the far end — inert"
+
+
+def test_P4_degenerate_triples_are_dropped_not_divided_by():
+    assert P._shape_defect(1.0, 1.0, 2.0, 5.0, 2.0, 7.0) is None      # equal abscissae
+    assert P._shape_defect(1.0, 1.0, 2.0, 5.0, 3.0, 5.0) is None      # equal values
+    d = P._shape_defect(1.0, 1.0, 0.0, 0.0, 2.0, 2.0)                 # exactly linear
+    assert d is not None and d == pytest.approx(0.0)
+    assert P._pick_triple(1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0) is None
+
+
+def test_P5_no_mode_adds_an_evaluation():
+    for f, a, b in SMOOTH:
+        st = {}
+        _x, n, ok = P.pure_root(f, a, b, 1e-12, 300, similarity="ratio", scale="derived3",
+                                guard="credit", points="shape", direction="dissimilar",
+                                stats=st)
+        assert ok
+        assert st["triple_changed"] <= n - 2 and st["dir_changed"] <= n - 2, (st, n)
+
+
+def test_modes_are_validated():
+    with pytest.raises(ValueError):
+        P.pure_root(lambda t: t, -1.0, 1.0, 1e-10, 100, points="whatever")
+    with pytest.raises(ValueError):
+        P.pure_root(lambda t: t, -1.0, 1.0, 1e-10, 100, direction="whatever")
+    with pytest.raises(ValueError):       # a triple needs the three-point scale
+        P.pure_root(lambda t: t, -1.0, 1.0, 1e-10, 100, scale="derived", points="shape")
+
+
+def test_both_modes_still_solve():
+    for f, a, b in SMOOTH:
+        for kw in ({"points": "shape"}, {"direction": "dissimilar"},
+                   {"points": "shape", "direction": "dissimilar"}):
+            x, _n, ok = P.pure_root(f, a, b, 1e-12, 300, similarity="ratio",
+                                    scale="derived3", guard="credit", **kw)
+            assert ok and abs(f(x)) < 1e-6, (kw, a, b, x)