semantica/docs/reference/kg.md

title, description, icon

title	description	icon
Knowledge Graph Module	Graph construction, temporal models, analytics, and distance intelligence.	diagram-project

semantica.kg transforms extracted entities and relationships into structured, queryable knowledge graphs. It includes temporal support, a full suite of graph analytics algorithms, node embeddings, and Distance Intelligence (v0.5.0).

What You Get

• GraphBuilder — construct graphs from entities and relationships with automatic entity merging
• TemporalKnowledgeGraph — time-aware edges (valid_from/valid_until) and point-in-time queries (v0.4.0)
• DistanceCalculator — semantic neighborhoods, N×N distance matrices, and distance band classification (v0.5.0)
• CentralityCalculator — PageRank, degree, betweenness, closeness, eigenvector centrality
• CommunityDetector — Louvain, Leiden, Label Propagation, K-Clique community detection
• PathFinder — Dijkstra, A*, BFS, K-Shortest path algorithms
• LinkPredictor — Preferential Attachment, Jaccard, Adamic-Adar link prediction
• NodeEmbedder — Node2Vec, DeepWalk, Word2Vec structural embeddings

For conflict detection and advanced entity resolution, use `semantica.conflicts` and `semantica.deduplication` alongside this module.

<img src="/assets/img/diagrams/kg-structure.svg" alt="Knowledge graph entity and relation structure: Person, Organization, Location, Date nodes with typed labeled edges" style={{ width: '100%', borderRadius: '12px', margin: '0 0 24px' }} />

GraphBuilder

Constructs knowledge graphs from extracted entities and relationships:

from semantica.kg import GraphBuilder

builder = GraphBuilder(merge_entities=True)
kg = builder.build(entities=entities, relationships=relationships)

Method	Description
build(sources)	Build graph from multiple data sources
build_single_source(data)	Build graph from a single data source
merge_entities()	Deduplicate and merge entities during construction

Temporal Knowledge Graphs (v0.4.0)

Attach valid_from / valid_until time windows to nodes and edges for point-in-time queries and historical analysis:

from semantica.kg import TemporalKnowledgeGraph, TemporalGraphQuery
from datetime import datetime

tkg = TemporalKnowledgeGraph()

# Nodes and edges carry explicit validity windows
tkg.add_node("ceo_role",  valid_from=datetime(2020, 1, 1), valid_until=datetime(2023, 6, 1))
tkg.add_edge(
    "alice", "acme_corp", "ceo_of",
    valid_from=datetime(2020, 1, 1),
    valid_until=datetime(2023, 6, 1)
)

# Point-in-time snapshot
snapshot = tkg.at(datetime(2021, 6, 15))

# Diff between two snapshots
query = TemporalGraphQuery(tkg)
snapshot_2020 = query.at_time("2020-01-01")
snapshot_2023 = query.at_time("2023-01-01")
diff = snapshot_2023.minus(snapshot_2020)
print(f"New nodes since 2020: {len(diff.nodes)}")

Supports all 13 Allen interval algebra relations (before, after, meets, overlaps, during, starts, finishes, equals, and their inverses). OWL-Time export available.

Distance Intelligence (v0.5.0)

Semantic neighborhood exploration for any entity in the graph:

from semantica.kg import DistanceCalculator

calc = DistanceCalculator(kg)

# Semantic neighborhood of a single node
neighborhood = calc.semantic_neighborhood("Apple Inc.", radius=0.4)

# N×N pairwise distance matrix
matrix = calc.distance_matrix(["Apple Inc.", "Google", "Microsoft"])

# Classify nodes into distance bands: "near" | "mid" | "far"
bands = calc.classify_bands(neighborhood)

Graph Analytics

Centrality Analysis

from semantica.kg import CentralityCalculator

calculator = CentralityCalculator()

centrality    = calculator.calculate_degree_centrality(graph)
pagerank      = calculator.calculate_pagerank(graph, damping_factor=0.85)
betweenness   = calculator.calculate_betweenness_centrality(graph)
closeness     = calculator.calculate_closeness_centrality(graph)
eigenvector   = calculator.calculate_eigenvector_centrality(graph)
all_metrics   = calculator.calculate_all_centrality(graph)

top_nodes = calculator.get_top_nodes(centrality, top_k=10)

Method	Algorithm
calculate_degree_centrality()	Degree-based importance
calculate_betweenness_centrality()	Bridge-based importance (bottleneck nodes)
calculate_closeness_centrality()	Distance-based importance
calculate_eigenvector_centrality()	Influence-based importance
calculate_pagerank()	Link-based importance (PageRank)
calculate_all_centrality()	All measures at once

Community Detection

from semantica.kg import CommunityDetector

detector = CommunityDetector()

# Louvain (default — fast, high quality)
communities = detector.detect_communities(graph, algorithm="louvain")

# Leiden (higher quality, slower)
leiden_communities = detector.detect_communities_leiden(graph, resolution=1.2)

metrics = detector.calculate_community_metrics(graph, communities)

Algorithms: Louvain, Leiden, Label Propagation, K-Clique Communities.

Path Finding

from semantica.kg import PathFinder

finder = PathFinder()

path   = finder.dijkstra_shortest_path(graph, "node_a", "node_b")
paths  = finder.all_shortest_paths(graph, "source", "target")
k_paths = finder.find_k_shortest_paths(graph, "source", "target", k=3)

Algorithms: Dijkstra, A*, BFS, All Shortest Paths, K-Shortest Paths.

Link Prediction

from semantica.kg import LinkPredictor

predictor = LinkPredictor(method="preferential_attachment")
links = predictor.predict_links(graph, top_k=20)
score = predictor.score_link(graph, "node_a", "node_b")

Algorithms: Preferential Attachment, Common Neighbors, Jaccard, Adamic-Adar, Resource Allocation.

Node Embeddings

from semantica.kg import NodeEmbedder

embedder = NodeEmbedder(method="node2vec", embedding_dimension=128)
embeddings   = embedder.compute_embeddings(graph_store, ["Entity"], ["RELATED_TO"])
similar_nodes = embedder.find_similar_nodes(graph_store, "entity_123", top_k=10)

Algorithms: Node2Vec, DeepWalk, Word2Vec.

Algorithm Summary

Category	Algorithms	Use Cases
Node Embeddings	Node2Vec, DeepWalk, Word2Vec	Structural similarity, node representation
Similarity	Cosine, Euclidean, Manhattan, Correlation	Node matching, recommendation
Path Finding	Dijkstra, A*, BFS, K-Shortest	Route planning, network analysis
Link Prediction	Preferential Attachment, Jaccard, Adamic-Adar	Network completion
Centrality	Degree, Betweenness, Closeness, PageRank	Influence analysis
Community Detection	Louvain, Leiden, Label Propagation	Social clustering
Connectivity	Components, Bridges, Density	Network robustness

Configuration

kg:
  resolution:
    threshold: 0.9
    strategy: semantic

  temporal:
    enabled: true
    default_validity: infinite

Persist graphs in Neo4j, FalkorDB, or Apache AGE. Source of entities and relationships fed to GraphBuilder. Visualize knowledge graphs interactively. Conflict detection and resolution.

Cookbooks

• Building Knowledge Graphs — fundamentals of KG construction · Beginner
• Your First Knowledge Graph — entity extraction to visualization · Beginner
• Graph Analytics — centrality and community detection · Intermediate
• Advanced Graph Analytics — PageRank, Louvain, shortest path · Advanced
• Temporal Knowledge Graphs — temporal logic and graph evolution · Advanced