Empirical Semantics

Wouter Beek (w.g.j.beek@vu.nl)

What is Empirial Semantics?

The empirical (i.e., non-analytic) analysis of meaning.

(We still use model theory and other formalisms in order to describe the outcomes of our analyses. But we do use formalisms in order to prescribe what a given expressions should mean.)

The problem of identity

Anyone can say anything about anything.
Anyone can say that anything is identical to anything (and they do).
Anyone can say anything, but not everyone is a logician.

bbc:sameAs
bbc:sameAs
owl:sameAs
?

Leibniz's Law

$$a = b \leftrightarrow (\forall \phi \in \Psi)(\phi(a) = \phi(b))$$

Pragmatics of owl:sameAs

Include links to other URIs. so that they can discover more things
Tim Berners-Lee, Linked Data, 2016

Relatedness cannot replace identity

SKOS exactMatch indicates a high degree of confidence that two concepts can be used interchangeably across a wide range of information retrieval applications.
From the SKOS standard

Identity does not hold across modal contexts

Lois Lane was rescued by Superman
Superman is Clark Kent
⊨ Lois Lane was rescued by Clark Kent
Lois Lane believes that she was rescued by Superman
Superman is Clark Kent
⊭ Lois Lane believes that she was rescued by Clark Kent

Indentity is context-dependent

Baspirin™ is the same as Caspirin™
Baspirin™ is not the same as Caspirin™

Identity over time

TODO

Identity under counterfactual assertion

Any property ascribed can be negated in a counterfactual.

Example

“If my parents would not have met then I would not have been born.”

Existing ‘solutions’

weaker alternatives
(e.g. relatedness)
Everything is related to everything.
domain-specific identity
“the same chemical” or “the same product”
Mutual agreement
Adding an owl:sameAs link requires approval from the authority that is being linked to.
Naming authority
Enforce the Unique Name Assumption (UNA).

Naming

Empirical Semantics: Approach

Take a meta-assertion from Analytic Semantics and evaluate them empirically WRT Big Data on the Web.

Example

Names are chosen arbitrarily and have no meaning.

Names on the Web

Quantifying the meaning of names

FORMAL
MEANING
NAMES

encode(FORMAL_MEANING) + encode(NAMES)

- encode(FORMAL_MEANING + NAMES)

= Mutual Information

Two hypotheses

$H_X$
Names do not encode predicate information.
$H_Y$
Names do not encode type information.

Evaluated over 600,000 datasets

S. De Rooij & W. Beek & P. Bloem & S. Schlobach & F. Van Harmelen, “Are Names Meaningful? Quantifying Social Meaning on the Semantic Web”, ISWC, 2016.

Semantics & Graph Structure

skos:exactMatch
foaf:knows
osspr:contains
geopolitics:hasBorderWidth

Social Meaning

Formal semantics cannot capture all meaning

Graph G₁

id:store def:sells id:tent.
id:tent  def:costs "¥150,000".
id:tent  rdf:type  id:Product.

Graph G₂

fy:aHup   pe:ko9sap_ fy:jufn12.
fy:jufn12 pe:oao9_   "Ufou".
fy:jufn12 rdf:type   fyufnt:tmffqt.

Graphs G₁ and G₂ are true in the same models.

Social Meaning

“An RDF graph may contain "defining information" that is opaque to logical reasoners. This information may be used by human interpreters of RDF information.”
“Human publishers of RDF content commit themselves to the mechanically-inferred social obligations.”
“The meaning of an RDF document includes the social meaning, the formal meaning, and the social meaning of the formal entailments.”
Part of an early working version of the RDF standard (link).

2 notions of meaning

Formal meaning

Social meaning

Domain & range

Examples drawn from BioPortal

bpo:has_event rdfs:domain bpo:person.
bpo:has_event rdfs:domain bpo:event.
bpo:has_event rdfs:domain bpo:disease.
  • What is the formal meaning?
  • What is the intended meaning?
  • How is this related to the OWA?

Thank you for your attention!