Agent Skills: Bifurcation

Hopf bifurcation detection for dynamical system state transitions with GF(3) phase portraits

UncategorizedID: plurigrid/asi/bifurcation

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plugins/asi/skills/bifurcation/SKILL.md

Skill Metadata

Name
bifurcation
Description
Hopf bifurcation detection for dynamical system state transitions with GF(3) phase portraits

Bifurcation

Detects and navigates bifurcation points in dynamical systems where qualitative behavior changes.

Trit: 0 (ERGODIC - Coordinator between stable states) Color: #9966FF (Purple - neutral zone bridging warm/cold)


Core Concepts

Bifurcation Types

| Type | Description | GF(3) Mapping | |------|-------------|---------------| | Saddle-Node | Two equilibria collide and annihilate | PLUS ↔ MINUS collision | | Hopf | Equilibrium → limit cycle | ERGODIC spawns oscillation | | Pitchfork | Symmetry-breaking | One ERGODIC → two ±PLUS/MINUS | | Transcritical | Exchange of stability | PLUS ↔ MINUS swap roles | | Period-Doubling | Route to chaos | Trit cascade: 0 → 1 → -1 → 0... |


Hopf Bifurcation Detection

import numpy as np
from scipy.linalg import eig

def detect_hopf(jacobian_fn, params, param_name, param_range):
    """
    Detect Hopf bifurcation by finding where eigenvalues cross imaginary axis.

    At Hopf bifurcation:
    - Pair of complex conjugate eigenvalues
    - Real part crosses zero
    - Imaginary part nonzero (oscillation frequency)
    """
    bifurcation_points = []

    for p in param_range:
        params[param_name] = p
        J = jacobian_fn(params)
        eigenvalues = eig(J)[0]

        # Find complex conjugate pairs
        for ev in eigenvalues:
            if np.abs(np.imag(ev)) > 1e-6:  # Has imaginary part
                if np.abs(np.real(ev)) < 1e-4:  # Real part near zero
                    bifurcation_points.append({
                        'param': p,
                        'eigenvalue': ev,
                        'frequency': np.abs(np.imag(ev)),
                        'type': 'hopf'
                    })

    return bifurcation_points

GF(3) Phase Portrait

def gf3_phase_portrait(system_fn, x_range, y_range, trit_classifier):
    """
    Generate phase portrait with GF(3) coloring.

    Each region colored by dominant behavior:
    - PLUS (+1): Expanding/generating (warm hues)
    - ERGODIC (0): Neutral/cycling (neutral hues)
    - MINUS (-1): Contracting/validating (cold hues)
    """
    X, Y = np.meshgrid(x_range, y_range)
    U, V = system_fn(X, Y)

    # Classify each point by local behavior
    trits = np.zeros_like(X)
    for i in range(X.shape[0]):
        for j in range(X.shape[1]):
            trits[i,j] = trit_classifier(U[i,j], V[i,j])

    # Color map: -1 → blue, 0 → green, +1 → red
    colors = {-1: '#0066FF', 0: '#00FF66', 1: '#FF6600'}

    return X, Y, U, V, trits, colors

Bifurcation Diagram Generator

#!/usr/bin/env bb
(require '[babashka.process :as p])

(defn logistic-map [r x]
  (* r x (- 1 x)))

(defn iterate-map [f x0 n-transient n-samples]
  "Iterate map, discard transient, collect samples"
  (let [trajectory (iterate (partial f) x0)
        post-transient (drop n-transient trajectory)]
    (take n-samples post-transient)))

(defn bifurcation-diagram [r-range x0 n-transient n-samples]
  "Generate bifurcation diagram data"
  (for [r r-range]
    {:r r
     :attractors (distinct
                   (iterate-map #(logistic-map r %) x0 n-transient n-samples))
     :period (count (distinct
                      (iterate-map #(logistic-map r %) x0 n-transient n-samples)))}))

;; Detect period-doubling cascade (route to chaos)
(defn period-doubling-points [diagram]
  "Find r values where period doubles"
  (loop [prev nil
         points []
         remaining diagram]
    (if (empty? remaining)
      points
      (let [curr (first remaining)
            period (:period curr)]
        (if (and prev (= (* 2 (:period prev)) period))
          (recur curr (conj points (:r curr)) (rest remaining))
          (recur curr points (rest remaining)))))))

State Transition Detection

class BifurcationMonitor:
    """
    Monitor system for bifurcation events in real-time.
    """

    def __init__(self, state_dim, history_len=100):
        self.state_dim = state_dim
        self.history = []
        self.history_len = history_len
        self.current_regime = 'unknown'

    def update(self, state, params):
        self.history.append({'state': state, 'params': params})
        if len(self.history) > self.history_len:
            self.history.pop(0)

        # Detect regime changes
        new_regime = self._classify_regime()
        if new_regime != self.current_regime:
            self._on_bifurcation(self.current_regime, new_regime)
            self.current_regime = new_regime

    def _classify_regime(self):
        """Classify current dynamical regime"""
        if len(self.history) < 10:
            return 'transient'

        states = np.array([h['state'] for h in self.history[-50:]])
        variance = np.var(states, axis=0)

        if np.all(variance < 1e-6):
            return 'fixed_point'  # MINUS: stable
        elif self._is_periodic(states):
            return 'limit_cycle'  # ERGODIC: oscillating
        else:
            return 'chaotic'  # PLUS: generating complexity

    def _is_periodic(self, states, tol=1e-3):
        """Check if trajectory is periodic"""
        # Simple periodicity check via autocorrelation
        for period in range(2, len(states)//2):
            if np.allclose(states[:-period], states[period:], atol=tol):
                return True
        return False

    def _on_bifurcation(self, old_regime, new_regime):
        """Handle bifurcation event"""
        trit_map = {
            'fixed_point': -1,  # MINUS: stable attractor
            'limit_cycle': 0,   # ERGODIC: periodic orbit
            'chaotic': 1        # PLUS: strange attractor
        }

        old_trit = trit_map.get(old_regime, 0)
        new_trit = trit_map.get(new_regime, 0)

        print(f"BIFURCATION: {old_regime} ({old_trit}) → {new_regime} ({new_trit})")
        print(f"GF(3) delta: {new_trit - old_trit}")

Triadic Bifurcation Analysis

When analyzing bifurcations, deploy three parallel agents:

PLUS (+1) Agent: Explore parameter space forward (increase control parameter)
ERGODIC (0) Agent: Monitor current state, detect oscillations
MINUS (-1) Agent: Analyze stability, compute Lyapunov exponents

Conservation: +1 + 0 + (-1) = 0 ✓

Integration with ruler-maximal

;; In ruler-maximal session initialization
(defn check-skill-bifurcation [skill-state]
  "Detect if skill loading pattern is approaching bifurcation"
  (let [usage-variance (variance (vals (:usage-counts skill-state)))
        load-frequency (/ (count (:loaded-skills skill-state))
                          (:session-duration skill-state))]
    (cond
      (< usage-variance 0.1) :fixed-point   ;; Stable usage pattern
      (periodic? (:load-history skill-state)) :limit-cycle  ;; Cyclic loading
      :else :exploring)))  ;; Still exploring skill space

Commands

# Analyze system for bifurcations
bb -e '(bifurcation/analyze system params)'

# Generate bifurcation diagram
bb scripts/bifurcation_diagram.bb --param r --range "2.5:4.0:0.001"

# Monitor real-time state transitions
bb scripts/bifurcation_monitor.bb --system lorenz

References

  • Strogatz, "Nonlinear Dynamics and Chaos" (2015)
  • Kuznetsov, "Elements of Applied Bifurcation Theory" (2004)
  • Guckenheimer & Holmes, "Nonlinear Oscillations, Dynamical Systems, and Bifurcations of Vector Fields"

Related Skills

  • dynamical-systems (0): General dynamical systems theory
  • chaos-theory (+1): Strange attractors, sensitivity to initial conditions
  • stability-analysis (-1): Lyapunov exponents, basin boundaries
  • ruler-maximal (0): Uses bifurcation for skill state transitions
  • gay-mcp (0): GF(3) color mapping for phase portraits