Neuro-Symbolic AI: Merging LLMs with Logic & Knowledge Graphs

package com.devmetrix.neurosymbolic;

import org.springframework.stereotype.Service;
import org.neo4j.driver.Driver;
import org.neo4j.driver.Session;
import org.springframework.ai.chat.ChatClient;
import java.util.List;
import java.util.Map;

@Service
public class KnowledgeGraphService {

    private final ChatClient chatClient;
    private final Driver neo4jDriver; // Neo4j Java Driver

    public KnowledgeGraphService(ChatClient chatClient, Driver neo4jDriver) {
        this.chatClient = chatClient;
        this.neo4jDriver = neo4jDriver;
    }

    /**
     * Ingests a text block and converts it to graph nodes/edges
     */
    public void ingestDocument(String content) {
        // 1. Prompt LLM to extract triples
        // We ask for a strict JSON format to ensure parsability
        String prompt = """
            You are a Knowledge Graph extraction engine.
            Extract all entities and relationships from the text below.
            Ignore generic entities like 'it' or 'they'.
            Format: JSON list of objects with keys: subject, predicate, object, subjectType, objectType.

            Text: """ + content;

        String jsonResponse = chatClient.call(prompt).getResult().getOutput().getContent();
        List<Triple> triples = parseJson(jsonResponse); // Custom JSON parser

        // 2. Insert into Neo4j
        // We use MERGE to avoid duplicates (idempotency)
        try (Session session = neo4jDriver.session()) {
            for (Triple t : triples) {
                session.run("""
                    MERGE (s:Entity {name: $sub})
                    ON CREATE SET s.type = $subType
                    MERGE (o:Entity {name: $obj})
                    ON CREATE SET o.type = $objType
                    MERGE (s)-[r:RELATION {type: $pred}]-&gt;(o)
                    """,
                    Map.of(
                        "sub", t.subject(),
                        "subType", t.subjectType(),
                        "obj", t.object(),
                        "objType", t.objectType(),
                        "pred", formatPredicate(t.predicate())
                    )
                );
            }
        }
    }

    private String formatPredicate(String pred) {
        return pred.toUpperCase().replace(" ", "_");
    }

    // Java 17+ Record for immutable data
    record Triple(String subject, String predicate, String object, String subjectType, String objectType) {}
}

'use client';

import dynamic from 'next/dynamic';
import { useState, useEffect } from 'react';

// Dynamic import to avoid SSR issues with canvas/window
const ForceGraph2D = dynamic(() => import('react-force-graph-2d'), { ssr: false });

export default function KnowledgeVisualizer({ graphData }) {
  // graphData format: { nodes: [{id: 'Elon'}, {id: 'Tesla'}], links: [{source: 'Elon', target: 'Tesla', label: 'CEO'}] }

  const [dimensions, setDimensions] = useState({ w: 800, h: 500 });

  useEffect(() => {
    // Responsive resizing logic here
    setDimensions({ w: window.innerWidth, h: 500 });
  }, []);

  return (
    <div className="border border-purple-500/30 rounded-xl overflow-hidden bg-gray-900 h-[500px] relative">
      <div className="absolute top-4 left-4 z-10 bg-black/70 p-2 rounded text-xs text-white border border-gray-700">
        <span className="text-purple-400 font-bold">● Entities:</span> {graphData.nodes.length} <br/>
        <span className="text-gray-400 font-bold">― Relations:</span> {graphData.links.length}
      </div>

      <ForceGraph2D
        width={dimensions.w}
        height={dimensions.h}
        graphData={graphData}
        nodeLabel="id"
        nodeColor={node => node.type === 'Person' ? '#8b5cf6' : '#10b981'} // Conditional coloring
        linkColor={() => '#4b5563'} // Gray links
        nodeRelSize={6}
        linkDirectionalArrowLength={3.5}
        linkDirectionalArrowRelPos={1}
        linkCurvature={0.25}
        backgroundColor="#111827" // dark-gray-900
        cooldownTicks={100}
        onNodeClick={node => alert(`You clicked ${node.id}`)}
      />
    </div>
  );
}