In 2026, the technical standard has shifted from a Skills Taxonomy to a Skills Ontology.

• Taxonomy (Hierarchical): A flat, rigid list of skills categorized into buckets (e.g., IT -> Software -> Java). These require manual updates and quickly become obsolete.

• Ontology (Relational): A multi-dimensional "Knowledge Graph" that understands relationships. It recognizes that "Data Analysis" is related to "SQL," "Python," and "Critical Thinking."

An ontology allows the platform to identify "Skill Adjacencies." For example, if an employee has high proficiency in "Adobe Premiere," the platform can infer a $70$% baseline proficiency in "Final Cut Pro," even if the employee has never listed it. This document explores the mathematical weighting of these relationships and how they drive internal mobility