Reasoning layer: analogy/induction/abduction/causal/planning over §5 geometry ops

Compose the live relational-neighborhood geometry OPERATORS into five reasoning
modes as pure, read-only C (engram_reason.{h,c}); each is proven with closed-form
constructed tests before it ships, not declared.

- ANALOGY  (Procrustes R + residual translation, apply to C, rank candidates)
- INDUCTION (combine-pooled rule geometry + point-to-manifold membership)
- ABDUCTION (best-explaining structure by point-to-manifold fit)
- CAUSAL   (centroid-cosine correlation vs directed influence: temporal
            precedence + association surviving confounder control via subtract;
            emits a correlation-vs-causation flag)
- PLANNING (geo-distance edges + Dijkstra → discrete geodesic path)

A shared point-to-manifold fit primitive underlies induction membership and
abduction ranking. engram/test/run_reason_tests.sh: 33/33 checks on both PERF
and ASan/UBSan passes; macOS leaks 0/0.

ANALOGY is surfaced as an el builtin (engram_reason_analogy_json) via the same
pass-through the §5 operators use — demonstrated callable from compiled El with a
container-capped fold (no self-host fold). The other four are C-layer only: their
set/point/timestamp inputs do not map to the flat-CSV el ABI without touching
codegen (deferred). engram_reason.c must join the server link line beside
engram_geometry.c at cutover. See docs/runbooks/2026-08-13-reasoning-operators-*.
This commit is contained in:
2026-08-13 01:33:14 -05:00
parent 85eee42106
commit a3358dfc95
8 changed files with 868 additions and 0 deletions
+27
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@@ -7446,6 +7446,7 @@ static char* engram_first_n_chars(const char* s, size_t n) {
#include "engram_store.h"
#include "engram_vindex.h" /* M8: ANN (HNSW) index for activation seed selection */
#include "engram_geometry.h" /* M9: centered relational-neighborhood geometry (priming) */
#include "engram_reason.h" /* reasoning layer: compositions over the §5 operators */
/* M10 REIFICATION: resident loaded form of the first-class persisted neighborhood
* records (Neighborhood + GeoMeanFrame). Built once at boot from the durable store
@@ -12395,6 +12396,32 @@ el_val_t engram_geo_analogy_json(el_val_t a_seeds, el_val_t b_seeds) {
return el_wrap_str(b.buf);
}
/* engram_reason_analogy_json(a_csv, b_csv, c_csv) — REASONING: "A:B :: C:?".
* Learns the AB transform (Procrustes rotation + residual translation) and applies
* it to C, returning the predicted point + the Procrustes frame-fit residual. This
* is the analogy MODE (engram_reason.c) surfaced over the same flat-CSV seed ABI as
* the §5 operators. The remaining reasoning modes (induction/abduction/causal/
* planning) take candidate-set / point / timestamp inputs that do not map to flat
* CSV and are C-layer only for now (see the reasoning-operators runbook). */
el_val_t engram_reason_analogy_json(el_val_t a_seeds, el_val_t b_seeds, el_val_t c_seeds) {
GeoDescriptor* A = eg_geo_build_desc(EL_CSTR(a_seeds));
GeoDescriptor* B = eg_geo_build_desc(EL_CSTR(b_seeds));
GeoDescriptor* C = eg_geo_build_desc(EL_CSTR(c_seeds));
if (!A || !B || !C) { if (A) engram_geo_free(A); if (B) engram_geo_free(B); if (C) engram_geo_free(C); return eg_geo_err("geometry unavailable"); }
GeoAnalogyResult res; char t[80]; JsonBuf b; jb_init(&b);
if (engram_reason_analogy(A, B, C, NULL, 0, &res) != 0) {
engram_geo_free(A); engram_geo_free(B); engram_geo_free(C);
return eg_geo_err("dim/frame mismatch or missing centroid");
}
jb_putc(&b, '{');
snprintf(t, sizeof t, "\"dim\":%d,\"analogy_residual\":%.6g", res.dim, res.analogy_residual); jb_puts(&b, t);
jb_puts(&b, ",\"mapped_point\":"); eg_geo_emit_vec(&b, res.mapped_point, res.dim);
jb_putc(&b, '}');
engram_reason_analogy_free(&res);
engram_geo_free(A); engram_geo_free(B); engram_geo_free(C);
return el_wrap_str(b.buf);
}
el_val_t engram_neighbors_json(el_val_t node_id, el_val_t max_depth, el_val_t direction) {
/* Re-implement here directly so we serialize without going through
* the ElList path. Walks BFS to max_depth, emits {node, edge, hops}
+4
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@@ -630,6 +630,10 @@ el_val_t engram_geo_subtract_json(el_val_t a_seeds, el_val_t b_seeds, el_val_t
el_val_t engram_geo_combine_json(el_val_t a_seeds, el_val_t b_seeds);
el_val_t engram_geo_distance_json(el_val_t a_seeds, el_val_t b_seeds);
el_val_t engram_geo_analogy_json(el_val_t a_seeds, el_val_t b_seeds);
/* reasoning layer (compositions over §5 operators). ANALOGY maps cleanly to the
* flat-CSV seed ABI; the other modes take set/point/timestamp inputs deferred from
* this ABI (see engram_reason.h / the reasoning-operators runbook). */
el_val_t engram_reason_analogy_json(el_val_t a_seeds, el_val_t b_seeds, el_val_t c_seeds);
el_val_t engram_consolidate_permanence(el_val_t node_id);
el_val_t engram_age_field(el_val_t delta_ms);
el_val_t engram_age_field_catchup(void);
+4
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@@ -1114,6 +1114,10 @@ el_val_t __engram_geo_distance_json(el_val_t a_seeds, el_val_t b_seeds) {
el_val_t __engram_geo_analogy_json(el_val_t a_seeds, el_val_t b_seeds) {
return engram_geo_analogy_json(a_seeds, b_seeds);
}
/* reasoning layer — ANALOGY native wrapper (same C-table wiring as the §5 ops). */
el_val_t __engram_reason_analogy_json(el_val_t a_seeds, el_val_t b_seeds, el_val_t c_seeds) {
return engram_reason_analogy_json(a_seeds, b_seeds, c_seeds);
}
el_val_t __engram_consolidate_permanence(el_val_t node_id) {
return engram_consolidate_permanence(node_id);
+287
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@@ -0,0 +1,287 @@
/* engram_reason.c — the REASONING layer. Pure compositions over engram_geometry.h.
* stdlib + libm only; READ-ONLY over its descriptor inputs; touches no store/index. */
#include "engram_reason.h"
#include <stdlib.h>
#include <string.h>
#include <math.h>
/* ── small float-vector helpers ─────────────────────────────────────────────── */
static double vdot(const float* a, const float* b, int dim) {
double s = 0; for (int i = 0; i < dim; i++) s += (double)a[i] * (double)b[i]; return s;
}
static double vnorm(const float* a, int dim) { return sqrt(vdot(a, a, dim)); }
static double vcos(const float* a, const float* b, int dim) {
double na = vnorm(a, dim), nb = vnorm(b, dim);
if (na < 1e-12 || nb < 1e-12) return 0.0; /* a null vector ⇒ no direction */
double c = vdot(a, b, dim) / (na * nb);
if (c > 1.0) c = 1.0; if (c < -1.0) c = -1.0;
return c;
}
static double l2(const float* a, const float* b, int dim) {
double s = 0; for (int i = 0; i < dim; i++) { double d = (double)a[i] - (double)b[i]; s += d * d; }
return sqrt(s);
}
/* ═══════════════════════════════════════════ SHARED — point-to-manifold FIT ══ */
int engram_reason_point_fit(const GeoDescriptor* g, const float* x,
double ext_floor, GeoFit* out) {
if (!g || !x || !out || g->dim <= 0 || !g->centroid) return -1;
if (!(ext_floor > 0)) ext_floor = 1.0;
int dim = g->dim;
/* residual r = x centroid */
double rr = 0; /* ‖r‖² */
float* r = malloc((size_t)dim * sizeof(float));
if (!r) return -1;
for (int i = 0; i < dim; i++) { double d = (double)x[i] - (double)g->centroid[i]; r[i] = (float)d; rr += d * d; }
double maha2 = 0, ss_in = 0; /* Mahalanobis² and in-subspace energy */
for (int k = 0; k < g->n_axes; k++) {
const float* ax = g->axes[k].axis; if (!ax) continue;
double proj = vdot(r, ax, dim); /* axes are orthonormal directions */
double den = g->axes[k].extent; if (den < ext_floor) den = ext_floor;
maha2 += (proj / den) * (proj / den);
ss_in += proj * proj;
}
double ortho2 = rr - ss_in; if (ortho2 < 0) ortho2 = 0; /* off-subspace energy */
double dist2 = maha2 + ortho2 / (ext_floor * ext_floor);
out->mahalanobis = sqrt(maha2);
out->ortho_residual = sqrt(ortho2);
out->distance = sqrt(dist2);
out->score = 1.0 / (1.0 + dist2);
free(r);
return 0;
}
/* ═══════════════════════════════════════════════════════════════ ANALOGY ════ */
int engram_reason_analogy(const GeoDescriptor* A, const GeoDescriptor* B,
const GeoDescriptor* C,
const GeoDescriptor* const* candidates, int n_candidates,
GeoAnalogyResult* out) {
if (!A || !B || !C || !out) return -1;
if (!A->centroid || !B->centroid || !C->centroid) return -1;
int dim = A->dim;
if (B->dim != dim || C->dim != dim) return -1;
memset(out, 0, sizeof *out);
out->dim = dim; out->best = -1;
/* Learn R_{A→B}. engram_geo_analogy(X,Y) yields R with apply(R, Y-axis) ≈ X-axis
* (R maps Y's frame → X's frame); so R that maps A→B is engram_geo_analogy(B,A). */
GeoAnalogy an;
if (engram_geo_analogy(B, A, &an) != 0) return -1;
out->analogy_residual = an.residual;
/* mapped = R·c_C + (c_B R·c_A) : the A→B affine (rotation + residual shift). */
float* RcA = malloc((size_t)dim * sizeof(float));
float* RcC = malloc((size_t)dim * sizeof(float));
out->mapped_point = malloc((size_t)dim * sizeof(float));
if (!RcA || !RcC || !out->mapped_point) { free(RcA); free(RcC); free(out->mapped_point); out->mapped_point = NULL; engram_geo_analogy_free(&an); return -1; }
engram_geo_analogy_apply(&an, A->centroid, RcA);
engram_geo_analogy_apply(&an, C->centroid, RcC);
for (int i = 0; i < dim; i++)
out->mapped_point[i] = (float)((double)RcC[i] + ((double)B->centroid[i] - (double)RcA[i]));
free(RcA); free(RcC);
engram_geo_analogy_free(&an);
/* nearest candidate to the mapped point (centroid L2). */
if (candidates && n_candidates > 0) {
out->n_candidates = n_candidates;
out->distances = malloc((size_t)n_candidates * sizeof(double));
if (!out->distances) return -1;
double best = -1; int bi = -1;
for (int i = 0; i < n_candidates; i++) {
const GeoDescriptor* cd = candidates[i];
double d = (cd && cd->centroid && cd->dim == dim) ? l2(out->mapped_point, cd->centroid, dim) : INFINITY;
out->distances[i] = d;
if (bi < 0 || d < best) { best = d; bi = i; }
}
out->best = bi; out->best_distance = best;
}
return 0;
}
void engram_reason_analogy_free(GeoAnalogyResult* r) {
if (!r) return;
free(r->mapped_point); free(r->distances);
r->mapped_point = NULL; r->distances = NULL;
}
/* ═══════════════════════════════════════════════════════════════ INDUCTION ══ */
int engram_reason_induce(const GeoDescriptor* const* examples, int n_examples,
int top_axes, double ext_floor, GeoInduction* out) {
if (!examples || n_examples < 1 || !out) return -1;
if (top_axes <= 0) top_axes = 8;
memset(out, 0, sizeof *out);
/* fold the examples left→right through the pooled-Gaussian combine. n==1 pools
* the single example with itself (identical cov ⇒ same shape, id-union = itself). */
GeoDescriptor* acc = engram_geo_combine(examples[0],
examples[n_examples > 1 ? 1 : 0], top_axes);
if (!acc) return -1;
for (int i = 2; i < n_examples; i++) {
GeoDescriptor* nxt = engram_geo_combine(acc, examples[i], top_axes);
engram_geo_free(acc);
if (!nxt) return -1;
acc = nxt;
}
out->rule = acc;
out->n_examples = n_examples;
out->ext_floor = (ext_floor > 0) ? ext_floor
: (acc->radius > 0 ? acc->radius * 0.25 : 1.0);
return 0;
}
double engram_reason_membership(const GeoInduction* ind, const float* x) {
if (!ind || !ind->rule || !x) return -1;
GeoFit f;
if (engram_reason_point_fit(ind->rule, x, ind->ext_floor, &f) != 0) return -1;
return f.score;
}
void engram_reason_induction_free(GeoInduction* out) {
if (!out) return;
if (out->rule) engram_geo_free(out->rule);
out->rule = NULL;
}
/* ═══════════════════════════════════════════════════════════════ ABDUCTION ══ */
int engram_reason_abduce(const float* obs, int dim,
const GeoDescriptor* const* hypotheses, int n,
double ext_floor, GeoAbduction* out) {
if (!obs || !hypotheses || n < 1 || dim <= 0 || !out) return -1;
if (!(ext_floor > 0)) ext_floor = 1.0;
memset(out, 0, sizeof *out);
out->n = n; out->best = -1;
out->scores = malloc((size_t)n * sizeof(double));
out->distances = malloc((size_t)n * sizeof(double));
out->rank = malloc((size_t)n * sizeof(int));
if (!out->scores || !out->distances || !out->rank) { engram_reason_abduction_free(out); return -1; }
double best = -1; int bi = -1;
for (int i = 0; i < n; i++) {
out->rank[i] = i;
const GeoDescriptor* h = hypotheses[i];
GeoFit f;
if (!h || h->dim != dim || engram_reason_point_fit(h, obs, ext_floor, &f) != 0) {
out->scores[i] = 0.0; out->distances[i] = INFINITY;
} else {
out->scores[i] = f.score; out->distances[i] = f.distance;
}
if (bi < 0 || out->scores[i] > best) { best = out->scores[i]; bi = i; }
}
out->best = bi; out->best_score = (bi >= 0) ? out->scores[bi] : 0.0;
/* rank indices best→worst by score (insertion sort — n is small). */
for (int i = 1; i < n; i++) {
int key = out->rank[i]; int j = i - 1;
while (j >= 0 && out->scores[out->rank[j]] < out->scores[key]) { out->rank[j + 1] = out->rank[j]; j--; }
out->rank[j + 1] = key;
}
return 0;
}
void engram_reason_abduction_free(GeoAbduction* out) {
if (!out) return;
free(out->scores); free(out->distances); free(out->rank);
out->scores = NULL; out->distances = NULL; out->rank = NULL;
}
/* ═══════════════════════════════════════════════════════════════════ CAUSAL ══ */
/* |cos| of two descriptors' centroids after removing confounder Z's subspace. */
static double controlled_assoc(const GeoDescriptor* x, const GeoDescriptor* y,
const GeoDescriptor* z) {
GeoResidual rx, ry; double c = 0;
int ox = engram_geo_subtract(x, z, 0, &rx);
int oy = engram_geo_subtract(y, z, 0, &ry);
if (ox == 0 && oy == 0 && rx.residual_centroid && ry.residual_centroid)
c = fabs(vcos(rx.residual_centroid, ry.residual_centroid, x->dim));
if (ox == 0) engram_geo_residual_free(&rx);
if (oy == 0) engram_geo_residual_free(&ry);
return c;
}
int engram_reason_causal(const GeoDescriptor* x, const GeoDescriptor* y,
const GeoDescriptor* const* confounders, int n_conf,
int64_t t_x, int64_t t_y,
double drop_frac, GeoCausal* out) {
if (!x || !y || !out || !x->centroid || !y->centroid || x->dim != y->dim) return -1;
if (!(drop_frac > 0 && drop_frac < 1)) drop_frac = 0.5;
memset(out, 0, sizeof *out);
const double assoc_floor = 0.2; /* below this = no meaningful association */
out->assoc_raw = fabs(vcos(x->centroid, y->centroid, x->dim));
/* control for each confounder; the strongest single explainer wins (min assoc). */
double ctrl = out->assoc_raw;
for (int i = 0; i < n_conf; i++) {
if (!confounders[i]) continue;
double c = controlled_assoc(x, y, confounders[i]);
if (c < ctrl) ctrl = c;
}
out->assoc_controlled = ctrl;
out->temporal_dir = (t_x < t_y) ? 1 : (t_x > t_y) ? -1 : 0;
if (out->assoc_raw < assoc_floor) {
out->verdict = GEO_CAUSAL_NONE;
} else if (ctrl < (1.0 - drop_frac) * out->assoc_raw && ctrl < assoc_floor) {
out->verdict = GEO_CAUSAL_CONFOUNDED; out->confounded = 1;
} else if (out->temporal_dir != 0) {
out->verdict = GEO_CAUSAL_DIRECTED; out->strength = ctrl;
} else {
out->verdict = GEO_CAUSAL_NONE; /* associated + robust but unorientable */
}
return 0;
}
/* ═══════════════════════════════════════════════════════════════════ PLANNING ══ */
int engram_reason_plan(const GeoDescriptor* const* nodes, int n,
int start, int goal, double neighbor_radius,
int use_wasserstein, GeoPlan* out) {
if (!nodes || n < 1 || !out) return -1;
if (start < 0 || start >= n || goal < 0 || goal >= n) return -1;
if (!(neighbor_radius > 0)) return -1;
memset(out, 0, sizeof *out);
/* dense edge weights (i<j symmetric); INFINITY = not adjacent. */
double* W = malloc((size_t)n * (size_t)n * sizeof(double));
if (!W) return -1;
for (int i = 0; i < n; i++) for (int j = 0; j < n; j++) W[(size_t)i * n + j] = (i == j) ? 0.0 : INFINITY;
for (int i = 0; i < n; i++) {
for (int j = i + 1; j < n; j++) {
GeoDistance d;
if (nodes[i] && nodes[j] && engram_geo_distance(nodes[i], nodes[j], &d) == 0) {
double w = use_wasserstein ? d.wasserstein2 : d.centroid_distance;
if (w <= neighbor_radius) { W[(size_t)i * n + j] = w; W[(size_t)j * n + i] = w; }
}
}
}
/* O(n²) Dijkstra. */
double* dist = malloc((size_t)n * sizeof(double));
int* prev = malloc((size_t)n * sizeof(int));
char* done = calloc((size_t)n, 1);
if (!dist || !prev || !done) { free(W); free(dist); free(prev); free(done); return -1; }
for (int i = 0; i < n; i++) { dist[i] = INFINITY; prev[i] = -1; }
dist[start] = 0;
for (int it = 0; it < n; it++) {
int u = -1; double bd = INFINITY;
for (int i = 0; i < n; i++) if (!done[i] && dist[i] < bd) { bd = dist[i]; u = i; }
if (u < 0) break;
done[u] = 1;
if (u == goal) break;
for (int v = 0; v < n; v++) {
double w = W[(size_t)u * n + v];
if (w < INFINITY && !done[v] && dist[u] + w < dist[v]) { dist[v] = dist[u] + w; prev[v] = u; }
}
}
if (dist[goal] < INFINITY) {
int len = 0; for (int v = goal; v != -1; v = prev[v]) len++;
out->path = malloc((size_t)len * sizeof(int));
if (out->path) {
out->path_len = len;
int idx = len - 1;
for (int v = goal; v != -1; v = prev[v]) out->path[idx--] = v;
out->total_cost = dist[goal];
out->reached = 1;
}
}
free(W); free(dist); free(prev); free(done);
return 0;
}
void engram_reason_plan_free(GeoPlan* out) {
if (!out) return;
free(out->path); out->path = NULL;
}
+161
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@@ -0,0 +1,161 @@
/* engram_reason.h — the REASONING layer: compositions over the §5 geometry
* OPERATORS (engram_geometry.h). Where the operators are a relational ALGEBRA over
* neighborhood descriptors, these are reasoning MODES built by CHAINING that algebra:
*
* ANALOGY A:B :: C:? — learn the A→B transform (Procrustes), apply to C.
* INDUCTION {E_i} → rule — pool example geometries; a generalizing structure
* + a membership test.
* ABDUCTION x → best H — the structure whose geometry best PLACES an
* observation in-distribution (inverse of prediction).
* CAUSAL x ? y | Z, t — separate mere overlap (correlation) from directed
* influence (temporal precedence + association that
* SURVIVES controlling for confounders via subtract).
* PLANNING start → goal — a trajectory (sequence of neighborhoods) through the
* manifold: shortest path over geo-distance edges.
*
* PURE + READ-ONLY (stdlib + libm only): every function consumes GeoDescriptor(s)
* (+ a few scalars / timestamps) and NEVER touches the store, index, or activation.
* All geometry is delegated to the engram_geo_* primitives; this file only composes.
*
* FRAME CONTRACT (inherited): descriptors passed together MUST share emb `dim` and
* `global_mean` frame — exactly the §5 operator contract. A function returns <0 on
* a dim/frame mismatch or bad argument.
*/
#ifndef ENGRAM_REASON_H
#define ENGRAM_REASON_H
#include <stdint.h>
#include "engram_geometry.h"
/* ═══════════════════════════════════════════════════════════════════════════
* SHARED PRIMITIVE — point-to-manifold FIT. How well does a single point x sit
* inside a neighborhood's ellipsoid? Splits the residual (x centroid) into:
* - the IN-SUBSPACE part, scaled by each axis extent → a Mahalanobis distance
* (how many "radii" out along the modeled directions), and
* - the ORTHOGONAL part outside the retained axes → energy the model does not
* explain at all (charged at the extent floor).
* This is the common engine under INDUCTION's membership test and ABDUCTION's
* explanation ranking. ext_floor (>0) guards zero-extent axes / the null model.
* ═══════════════════════════════════════════════════════════════════════════ */
typedef struct {
double mahalanobis; /* sqrt( Σ_k ((a_k·(xc)) / max(ext_k,floor))² ) */
double ortho_residual; /* ‖(xc) projected off the retained axes‖ (raw L2) */
double distance; /* sqrt( maha² + (ortho_residual/floor)² ) — full fit */
double score; /* 1 / (1 + distance²) ∈ (0,1] (1 = dead-center) */
} GeoFit;
int engram_reason_point_fit(const GeoDescriptor* g, const float* x,
double ext_floor, GeoFit* out);
/* ═══════════════════════════════════════════════════════════════════════════
* ANALOGY — "A:B :: C:?". Learn the transform that carries A to B (orthogonal
* Procrustes rotation R between their principal frames + the residual translation),
* apply it to C, and return the mapped point + the nearest candidate neighborhood.
* Composes: engram_geo_analogy (R) + engram_geo_analogy_apply + engram_geo_distance.
* ═══════════════════════════════════════════════════════════════════════════ */
typedef struct {
int dim;
float* mapped_point; /* predicted D location = R·c_C + (c_B R·c_A) (owned)*/
double analogy_residual;/* Procrustes ‖AB R‖_F — frame-alignment quality */
int best; /* index of nearest candidate to mapped_point, or 1 */
double best_distance; /* centroid L2 from mapped_point to the winner */
int n_candidates;
double* distances; /* centroid L2 mapped_point→candidate[i] (owned)*/
} GeoAnalogyResult;
/* candidates may be NULL/0 (then best=1 and only mapped_point is filled). */
int engram_reason_analogy(const GeoDescriptor* A, const GeoDescriptor* B,
const GeoDescriptor* C,
const GeoDescriptor* const* candidates, int n_candidates,
GeoAnalogyResult* out);
void engram_reason_analogy_free(GeoAnalogyResult* r);
/* ═══════════════════════════════════════════════════════════════════════════
* INDUCTION — from a SET of example neighborhoods to the generalizing structure.
* Pools the examples (law-of-total-variance via engram_geo_combine, folded left to
* right) into a single "rule" descriptor whose top principal axes are the directions
* CONSISTENTLY present across the examples (the shared subspace surfaces as the
* dominant pooled axes; idiosyncratic per-example directions fall to the tail).
* The rule carries a membership test (point-to-manifold fit against the pool).
* ═══════════════════════════════════════════════════════════════════════════ */
typedef struct {
GeoDescriptor* rule; /* induced generalizing geometry (owned; geo_free) */
double ext_floor; /* extent floor used by the membership test */
int n_examples;/* how many examples were pooled */
} GeoInduction;
/* top_axes<=0 → 8. ext_floor<=0 → derived from the pooled radius. */
int engram_reason_induce(const GeoDescriptor* const* examples, int n_examples,
int top_axes, double ext_floor, GeoInduction* out);
/* Membership of a point in the induced rule ∈ (0,1] (the fit score). <0 on error. */
double engram_reason_membership(const GeoInduction* ind, const float* x);
void engram_reason_induction_free(GeoInduction* out);
/* ═══════════════════════════════════════════════════════════════════════════
* ABDUCTION — inference to the best explanation. Given an observation POINT, rank a
* set of candidate structures by how well each PLACES the observation in-distribution
* (min point-to-manifold distance = the structure that, if assumed, best accounts for
* the observation). The inverse of prediction.
* ═══════════════════════════════════════════════════════════════════════════ */
typedef struct {
int best; /* index of best-explaining hypothesis, or 1 */
double best_score;
int n;
double* scores; /* fit score per hypothesis (higher = better) (owned)*/
double* distances; /* explanation distance per hypothesis (owned)*/
int* rank; /* hypothesis indices sorted best→worst (owned)*/
} GeoAbduction;
int engram_reason_abduce(const float* obs, int dim,
const GeoDescriptor* const* hypotheses, int n,
double ext_floor, GeoAbduction* out);
void engram_reason_abduction_free(GeoAbduction* out);
/* ═══════════════════════════════════════════════════════════════════════════
* CAUSAL — correlation vs causation. Over two variables' geometries (+ candidate
* confounders + temporal order), distinguish:
* - mere co-occurrence / overlap (correlation), from
* - directed influence: association that (a) SURVIVES controlling for confounders
* (subtract each Z's subspace from both centroids, re-measure) and (b) is oriented
* by temporal PRECEDENCE.
* Composes: centroid cosine (correlation) + engram_geo_subtract (control) + timestamps.
* ═══════════════════════════════════════════════════════════════════════════ */
typedef enum {
GEO_CAUSAL_NONE = 0, /* no meaningful association */
GEO_CAUSAL_DIRECTED = 1, /* survives control + temporally ordered → cause→eff */
GEO_CAUSAL_CONFOUNDED = 2 /* correlated but association dies under control */
} GeoCausalVerdict;
typedef struct {
double assoc_raw; /* |cos(c_x,c_y)| — the raw correlation */
double assoc_controlled; /* |cos| of residual centroids after control */
int temporal_dir; /* +1 x→y, 1 y→x, 0 tie/unknown */
GeoCausalVerdict verdict;
int confounded; /* 1 iff verdict==CONFOUNDED (the flag) */
double strength; /* directed influence estimate ∈[0,1] (0 else)*/
} GeoCausal;
/* confounders may be NULL/0. t_x,t_y are comparable timestamps (any monotone unit);
* pass equal values for "unknown order". drop_frac∈(0,1): a controlled association
* below (1drop_frac)·assoc_raw AND below an absolute floor ⇒ CONFOUNDED. */
int engram_reason_causal(const GeoDescriptor* x, const GeoDescriptor* y,
const GeoDescriptor* const* confounders, int n_conf,
int64_t t_x, int64_t t_y,
double drop_frac, GeoCausal* out);
/* ═══════════════════════════════════════════════════════════════════════════
* PLANNING — trajectory construction. Given a set of neighborhoods (manifold nodes),
* a start and a goal, build a PATH (sequence of intermediate neighborhoods) by
* shortest path over the graph whose edges connect neighborhoods within
* neighbor_radius, weighted by geo-distance. Long straight jumps are not edges, so
* the path follows the manifold's curvature through intermediates (a discrete geodesic).
* Composes: engram_geo_distance (edge weights) + Dijkstra.
* ═══════════════════════════════════════════════════════════════════════════ */
typedef struct {
int* path; /* node indices start..goal (owned) */
int path_len;
double total_cost; /* summed centroid-distance edge weights along path */
int reached; /* 1 if goal reachable within neighbor_radius graph */
} GeoPlan;
/* neighbor_radius>0: max centroid distance for two neighborhoods to be adjacent.
* Use "wasserstein"!=0 to weight edges by Wasserstein-2 instead of centroid L2. */
int engram_reason_plan(const GeoDescriptor* const* nodes, int n,
int start, int goal, double neighbor_radius,
int use_wasserstein, GeoPlan* out);
void engram_reason_plan_free(GeoPlan* out);
#endif /* ENGRAM_REASON_H */