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Knowledge Base Embeddings: Semantics and Theoretical Properties

Camille Bourgaux, Ricardo Guimarães, Raoul Koudijs, Victor Lacerda, Ana Ozaki

TL;DR

Knowledge Base Embeddings extends KG embeddings to DL-based KBs (e.g., $ELHI_ot$, $ALC_p$) using region-based geometries, and introduces a formal semantic framework $S_M(E,L)$ to compare embedding methods along soundness, completeness, entailment closure, faithfulness, and expressiveness. It analyzes several methods (Convex Geometric, Cone-based al-cones, ELEm, ELBE, BoxEL, BoxE, ExpressivE) and shows that many do not simultaneously achieve all desirable properties; in finite DL languages many properties become equivalent. The study provides a principled lens for evaluating and guiding the design of KB embeddings with stronger theoretical guarantees, while highlighting core challenges such as encoding role disjointness and the bottom concept. It also suggests directions toward query-answering and explicit knowledge injection to broaden practical impact.

Abstract

Research on knowledge graph embeddings has recently evolved into knowledge base embeddings, where the goal is not only to map facts into vector spaces but also constrain the models so that they take into account the relevant conceptual knowledge available. This paper examines recent methods that have been proposed to embed knowledge bases in description logic into vector spaces through the lens of their geometric-based semantics. We identify several relevant theoretical properties, which we draw from the literature and sometimes generalize or unify. We then investigate how concrete embedding methods fit in this theoretical framework.

Knowledge Base Embeddings: Semantics and Theoretical Properties

TL;DR

Knowledge Base Embeddings extends KG embeddings to DL-based KBs (e.g., , ) using region-based geometries, and introduces a formal semantic framework to compare embedding methods along soundness, completeness, entailment closure, faithfulness, and expressiveness. It analyzes several methods (Convex Geometric, Cone-based al-cones, ELEm, ELBE, BoxEL, BoxE, ExpressivE) and shows that many do not simultaneously achieve all desirable properties; in finite DL languages many properties become equivalent. The study provides a principled lens for evaluating and guiding the design of KB embeddings with stronger theoretical guarantees, while highlighting core challenges such as encoding role disjointness and the bottom concept. It also suggests directions toward query-answering and explicit knowledge injection to broaden practical impact.

Abstract

Research on knowledge graph embeddings has recently evolved into knowledge base embeddings, where the goal is not only to map facts into vector spaces but also constrain the models so that they take into account the relevant conceptual knowledge available. This paper examines recent methods that have been proposed to embed knowledge bases in description logic into vector spaces through the lens of their geometric-based semantics. We identify several relevant theoretical properties, which we draw from the literature and sometimes generalize or unify. We then investigate how concrete embedding methods fit in this theoretical framework.
Paper Structure (22 sections, 45 theorems, 8 equations, 3 figures, 4 tables)

This paper contains 22 sections, 45 theorems, 8 equations, 3 figures, 4 tables.

Key Result

Proposition 1

Let $\mathcal{T}$ be an $\mathcal{L}$-TBox, $\mathcal{A}$ an ABox and $E\xspace$ an $M\xspace$-model of $\mathcal{K}\xspace=\mathcal{T}\xspace\cup\mathcal{A}\xspace$. Then the following holds.

Figures (3)

  • Figure 1: Relationships between the properties we consider (except for soundness which is incomparable and KB properties expressible by combining TBox and ABox properties). An arrow from property X to property Y indicates that property X implies property Y. A dashed line indicates that the implication holds when the TBox $\mathcal{T}\xspace$ is empty. The symbol $\forall$ defines a guarantee, while $\exists$ just posits ability.
  • Figure 2: Box$^2$EL-embedding.
  • Figure 3: Relationships between the properties when the DL language is finite. An arrow from X to Y indicates that X implies Y.

Theorems & Definitions (101)

  • Definition 1: Embedding method
  • Definition 2: Embedding semantics
  • Remark 1
  • Definition 3: $M$-model
  • Example 1
  • Example 2
  • Example 3
  • Example 4
  • Example 5
  • Example 6
  • ...and 91 more