checkpoint: port evolutionary and population dynamics

include/fces/fitness.hpp

@@ -59,19 +59,55 @@ private:
     float grokking_coefficient_;
 };
 
+/**
+ * FuzzySet represents a fuzzy set with a trapezoidal membership function.
+ */
+class FuzzySet {
+public:
+    FuzzySet(std::string name, float a, float b, float c, float d) noexcept
+        : name_(std::move(name)), a_(a), b_(b), c_(c), d_(d) {}
+
+    float membership(float x) const noexcept {
+        if (!std::isfinite(x)) {
+            return 0.0f;
+        }
+        if (x <= a_ || x >= d_) {
+            return 0.0f;
+        }
+        if (x >= b_ && x <= c_) {
+            return 1.0f;
+        }
+        if (x > a_ && x < b_) {
+            float range = b_ - a_;
+            return (x - a_) / (range > 0.0f ? range : 1e-9f);
+        }
+        if (x > c_ && x < d_) {
+            float range = d_ - c_;
+            return (d_ - x) / (range > 0.0f ? range : 1e-9f);
+        }
+        return 0.0f;
+    }
+
+    const std::string& name() const noexcept { return name_; }
+
+private:
+    std::string name_;
+    float a_;
+    float b_;
+    float c_;
+    float d_;
+};
+
 /**
  * Fitness metrics for multi-objective evaluation.
  */
 struct FitnessMetrics {
-    float loss_improvement = 0.0f;
-    float sparsity_score = 0.0f;
-    float stability_score = 0.0f;
-    float novelty_score = 0.0f;
-
-    /// Weighted combination
-    float total(float alpha = 0.7f, float beta = 0.3f) const {
-        return alpha * loss_improvement + beta * sparsity_score;
-    }
+    float training_advantage = 0.0f;
+    float validation_advantage = 0.0f;
+    float grad_cv = 0.0f;
+    float sparsity_delta = 0.0f;
+    float consistency_gap = 0.0f;
+    float stable_rank = 0.0f;
 };
 
 /**
@@ -79,12 +115,24 @@ struct FitnessMetrics {
  */
 class FuzzyFitnessEvaluator {
 public:
-    FitnessMetrics evaluate(
-        float loss_before,
-        float loss_after,
-        float sparsity = 0.0f,
-        float val_loss = -1.0f
-    ) const;
+    FuzzyFitnessEvaluator() noexcept;
+
+    float evaluate(const FitnessMetrics& metrics) const noexcept;
+
+private:
+    FuzzySet stability_set_;
+    FuzzySet train_set_;
+    FuzzySet val_set_;
+    FuzzySet sparsity_set_;
+    FuzzySet consistency_set_;
+    FuzzySet rank_set_;
+
+    float w_stability_ = 0.2f;
+    float w_train_ = 0.2f;
+    float w_val_ = 0.3f;
+    float w_sparsity_ = 0.1f;
+    float w_consistency_ = 0.2f;
+    float w_rank_ = 0.1f;
 };
 
 }  // namespace fces