Multi-GNN Recursive Kernel PCA Problem

You are tasked with designing a multi-layer trading strategy based on recursive Kernel PCA and interdependent 𝑁-Layer GNNs to analyze 𝑛=28 currency pairs. Each GNN layer specializes in capturing different graph dynamics (e.g., volatility, profitability, momentum), while layers interact nonlinearly and recursively. The outputs from each GNN layer influence:

The adjacency matrices for the other layers.
The kernel matrices for volatility (𝐾𝑉) and profitability (𝐾Π).
The node embeddings, which are combined and propagated across layers.
The challenge is to optimize the system by dynamically balancing these interactions while maximizing risk-adjusted profitability.

Enhanced Relationships Between 𝑁-Layer GNNs Interdependent GNN Layers
GNN Layer Types:

GNN1 : Models volatility relationships.
GNN2 : Models profitability dynamics.
GNN3 : Models momentum and correlation patterns.

Cross-Layer Interactions:

Outputs from GNN1 dynamically update edge weights in GNN2 :

A_2^{(t+1)}[i][j] = f(A_2^{(t)}[i][j], h_i^{1,(t)}, h_j^{1,(t)}),

where ℎ𝑖1(𝑡) is the embedding of node 𝑖 from GNN1.

Similarly, outputs from GNN2 influence GNN3 :

A_3^{(t+1)}[i][j] = g(A_3^{(t)}[i][j], h_i^{2,(t)}, h_j^{2,(t)}).

The final embeddings from GNN3 recursively update GNN1 :

A_1^{(t+1)}[i][j] = h(A_1^{(t)}[i][j], h_i^{3,(t)}, h_j^{3,(t)}).

Multi-Scale Aggregation:

Node embeddings are aggregated across all 𝑁 layers:

h_i^{final} = Σ_{l=1}^N W_l \cdot h_i^{l,(t)}.

Step-by-Step Mathematical Representation
Step 1: Node and Edge Features
Node Features (𝑥𝑖):

x_i = [\sigma_i(t), R_i(t), M_i(t), \rho_{i,j}(t)],

where:

𝜎𝑖(𝑡): Volatility.
𝑅𝑖(𝑡): Return.
𝑀𝑖(𝑡): Momentum.
𝜌𝑖,𝑗(𝑡): Correlation.
Edge Features (𝑒𝑖𝑗):

e_{ij} = [| \sigma_i(t) - \sigma_j(t) |, | R_i(t) - R_j(t) |, \rho_{i,j}(t)].

Adjacency Matrices:

For layer 𝑙:

A^{(l)}[i][j] = exp(-||x_i - x_j||^2 / (2 * \sigma^{(l)})).

Step 2: Multi-GNN Propagation Message Passing:

For each GNN layer 𝑙:

m_{ij}^{(l)} = A^{(l)}[i][j] * (W^{(l)} * h_j^{(l)}),

Node Update:

h_i^{(l+1)} = ReLU(Σ_{j ∈ N(i)} m_{ij}^{(l)} + b^{(l)}).

Cross-Layer Feedback:

Update edge weights in other layers:

A_{k}^{(t+1)}[i][j] = f(A_k^{(t)}[i][j], h_i^{l,(t)}, h_j^{l,(t)}),

where 𝑘≠𝑙.

Step 3: Kernel PCA
Kernel Updates:

Use embeddings ℎ𝑖𝑓𝑖𝑛𝑎𝑙 to update kernel matrices:

K_V[i][j] = exp(-||h_i^{final} - h_j^{final}||^2 / (2 * \sigma_V^2)),
K_\Pi[i][j] = exp(-||h_i^{final} - h_j^{final}||^2 / (2 * \sigma_\Pi^2)).

Eigenvalue Decomposition:

K = Σ_{k=1}^m λ_k * (v_k ⊗ v_k),

where 𝜆𝑘 and 𝑣𝑘 are eigenvalues and eigenvectors.

Step 4: Recursive Feedback

Recursive Edge Updates:

A^{(t+1)} = f(A^{(t)}, K_V^{(t)}, K_\Pi^{(t)}).

Recursive Kernel Updates:

K_V^{(t+1)} = g(A^{(t+1)}, K_\Pi^{(t)}),
K_\Pi^{(t+1)} = h(A^{(t+1)}, K_V^{(t)}).

Step 5: Neural Networks
Threshold Predictions:

Θ_V(t) = NN_1(R_{V,i}(t)),
Θ_\Pi(t) = NN_2(R_{\Pi,i}(t)).

Meta Neural Network:

Θ_{final}(t) = MetaNN(Θ_V(t), Θ_\Pi(t)).

Step 6: Trade Execution
Signal Calculation:

S_{i,j}(t) = R_{V,i}(t) / sqrt( Σ_{k=1}^n R_{V,k}(t)^2 ).

Execution Condition:

| S_{i,j}(t) | > Θ_{final}(t).

Constraints
Variance Explained:

Σ_{k=1}^m λ_k / Σ_{k=1}^n λ_k ≥ 0.90.

Dynamic Kernel Widths:

σ_V(t) = σ_V(0) * (1 + κ * StdDev(V(t))),
σ_\Pi(t) = σ_\Pi(0) * (1 + κ * StdDev(Π(t))).

Feedback Convergence:

max(|K_V^{(t+1)} - K_V^{(t)}|, |K_\Pi^{(t+1)} - K_\Pi^{(t)}|) < ε.

Objective
Maximize risk-adjusted profitability by:

Extracting dominant volatility and profitability components with Kernel PCA.
Propagating and aggregating embeddings across 𝑁-interdependent GNN layers.
Dynamically refining kernels and thresholds using recursive feedback.


Code
#define PAIRS 28

string CurrencyPairs[PAIRS] = {
    "EURUSD", "GBPUSD", "USDJPY", "GBPJPY", "USDCAD", "EURAUD", "EURJPY",
    "AUDCAD", "AUDJPY", "AUDNZD", "AUDUSD", "CADJPY", "EURCAD", "EURCHF",
    "EURGBP", "EURNZD", "GBPCAD", "GBPCHF", "NZDCAD", "NZDJPY", "NZDUSD",
    "USDCHF", "CHFJPY", "AUDCHF", "GBPNZD", "NZDCHF", "CADCHF", "GBPAUD"
};

vars volatilities[PAIRS];             // Volatility for each pair
vars adjacencyMatrices[PAIRS][PAIRS][28];  // Adjacency matrices for 28 GNNs
vars nodeEmbeddings[PAIRS][5][28];    // Node embeddings for 28 GNNs
vars updatedEmbeddings[PAIRS][5];     // Final node embeddings after aggregation
vars kernelMatrix[PAIRS][PAIRS];      // Kernel matrix for PCA
vars eigenvalues[PAIRS];              // Eigenvalues from PCA
vars eigenvectors[PAIRS][PAIRS];      // Eigenvectors from PCA
vars reducedMatrix[PAIRS][3];         // Reduced components from PCA
vars thresholds[PAIRS];               // Thresholds for trade execution
vars signals[PAIRS];                  // Final trading signals
int lookback = 50;
int NN;                               // Neural network handle for threshold prediction
int propagationDepth = 3;             // GNN propagation depth

// Step 1: Calculate volatilities for all pairs
function calculateVolatilities() {
    for (int i = 0; i < PAIRS; i++) {
        volatilities[i] = StdDev(series(price(CurrencyPairs[i])), lookback);
    }
}

// Step 2: Construct adjacency matrices for 28 GNNs
function constructAdjacencyMatrices() {
    for (int l = 0; l < 28; l++) { // For each GNN layer
        for (int i = 0; i < PAIRS; i++) {
            for (int j = 0; j < PAIRS; j++) {
                if (i != j) {
                    adjacencyMatrices[i][j][l] = exp(-pow(volatilities[i] - volatilities[j], 2) / (2 * 0.5^2)); // Gaussian kernel
                } else {
                    adjacencyMatrices[i][j][l] = 0; // No self-loops
                }
            }
        }
    }
}

// Step 3: Propagate embeddings for each GNN
function propagateEmbeddings() {
    for (int l = 0; l < 28; l++) { // For each GNN
        for (int t = 0; t < propagationDepth; t++) { // Propagation steps
            vars newEmbeddings[PAIRS][5];
            for (int i = 0; i < PAIRS; i++) {
                for (int k = 0; k < 5; k++) {
                    newEmbeddings[i][k] = 0;
                    for (int j = 0; j < PAIRS; j++) {
                        newEmbeddings[i][k] += adjacencyMatrices[i][j][l] * nodeEmbeddings[j][k][l];
                    }
                    newEmbeddings[i][k] = ReLU(newEmbeddings[i][k]);
                }
            }
            // Update embeddings
            for (int i = 0; i < PAIRS; i++) {
                for (int k = 0; k < 5; k++) {
                    nodeEmbeddings[i][k][l] = newEmbeddings[i][k];
                }
            }
        }
    }
}

// Step 4: Aggregate embeddings across all GNNs
function aggregateEmbeddings() {
    for (int i = 0; i < PAIRS; i++) {
        for (int k = 0; k < 5; k++) {
            updatedEmbeddings[i][k] = 0;
            for (int l = 0; l < 28; l++) {
                updatedEmbeddings[i][k] += nodeEmbeddings[i][k][l];
            }
            updatedEmbeddings[i][k] /= 28; // Average across GNNs
        }
    }
}

// Step 5: Update kernel matrix using aggregated embeddings
function updateKernelMatrix() {
    for (int i = 0; i < PAIRS; i++) {
        for (int j = 0; j < PAIRS; j++) {
            kernelMatrix[i][j] = exp(-dotProduct(updatedEmbeddings[i], updatedEmbeddings[j]) / (2 * 0.5^2)); // Gaussian kernel
        }
    }
}

// Step 6: Perform Kernel PCA
function performKernelPCA() {
    eigenDecomposition(kernelMatrix, eigenvalues, eigenvectors);
    for (int i = 0; i < PAIRS; i++) {
        for (int j = 0; j < 3; j++) { // Top 3 components
            reducedMatrix[i][j] = dotProduct(kernelMatrix[i], eigenvectors[j]);
        }
    }
}

// Step 7: Train neural network for threshold prediction
function trainNeuralNetwork() {
    LayerPerceptron(10);  // Hidden layer
    LayerNormalize();
    LayerPerceptron(1);   // Output layer
    NN = Train("ThresholdNN", reducedMatrix, thresholds, PAIRS);
}

// Step 8: Generate trade signals
function generateSignals() {
    for (int i = 0; i < PAIRS; i++) {
        signals[i] = Predict(NN, reducedMatrix[i]);
    }
}

// Step 9: Execute trades
function executeTrades() {
    for (int i = 0; i < PAIRS; i++) {
        if (signals[i] > 0.5) {
            enterLong(CurrencyPairs[i]);
        } else if (signals[i] < -0.5) {
            enterShort(CurrencyPairs[i]);
        }
    }
}

// Main function
function run() {
    set(PLOTNOW);

    // Step 1: Calculate volatilities
    calculateVolatilities();

    // Step 2: Construct adjacency matrices
    constructAdjacencyMatrices();

    // Step 3: Propagate embeddings for each GNN
    propagateEmbeddings();

    // Step 4: Aggregate embeddings
    aggregateEmbeddings();

    // Step 5: Update kernel matrix
    updateKernelMatrix();

    // Step 6: Perform Kernel PCA
    performKernelPCA();

    // Step 7: Train neural network for thresholds
    trainNeuralNetwork();

    // Step 8: Generate trade signals
    generateSignals();

    // Step 9: Execute trades
    executeTrades();
}