Senior Software Engineer, Ontology & Reasoning Systems (819)

Role Overview

Protegrity is seeking a Senior Software Engineer, Ontology & Reasoning Systems to design and build the ontology and reasoning layer that connects structured sources, semi-structured metadata, and unstructured documents into a model that supports deterministic machine reasoning.

What You’ll Do

• Own the ontology and rule layer that unifies structured, semi-structured, and unstructured enterprise data into a single reasoning model.
• Model entities, relationships, events, and constraints across heterogeneous sources, and develop rules that derive conclusions from combinations of facts.
• Use LLMs at the ingestion boundary for extraction, normalization, and categorization, with appropriate validation of model-generated outputs.
• Make system findings traceable by connecting each conclusion to the source facts and rules that produced it.
• Build retrieval capabilities, including vector search, keyword search, and graph traversal, to support reasoning workflows.
• Improve quality through entity resolution, constraint modeling, and structured handling of conflicting or overlapping sources.
• Ship production services and research prototypes with a focus on correctness, reliability, and maintainability.

What You’ll Need

• 5+ years of experience building backend systems in a modern language such as Python, Go, Java, Scala, Rust, or similar, or equivalent practical experience.
• A strong formal and mathematical foundation, including discrete mathematics, logic, and graph theory.
• The ability to reason about soundness, completeness, and tractability, and to express complex domains as formal rules and constraints.
• Hands-on experience with declarative, logic-based, or rule-based reasoning systems such as Datalog, Answer Set Programming, constraint logic programming, Prolog, production rule engines, SMT solvers, or similar.
• Practical experience building LLM-powered systems, including structured extraction, RAG, or classification pipelines, with sound judgment about where model outputs require validation.
• Deep experience with knowledge graphs and graph data, including RDF, SPARQL, property graphs, or graph databases such as Neo4j.
• Experience designing systems whose outputs trace back to their inputs, including provenance, derivation chains, or evidence trails.
• Strong debugging, testing, and validation practices, with attention to correctness.

Nice To Have

• Experience with constraint satisfaction or deductive reasoning, including CSP, unification, fixpoint or closure computation, or constraint propagation.
• Experience with formal ontology and semantics, including OWL, SHACL, description logics, or reasoners.
• Experience with LLM evaluation, entity resolution, citation validation, or hallucination reduction.
• Experience with symbolic computation, theorem proving, model checking, or formal verification.

Compensation Range

$237.6K - $266.7K