Symbolic AI & Neuro-Symbolic Integration
Formal knowledge representation, symbolic reasoning, and their integration with neural methods for knowledge structuring and consolidation pipelines.
Routing
- USE FOR: Symbolic AI, neuro-symbolic integration, knowledge representation and reasoning (KRR), ontology engineering, description logics, and hybrid symbolic-neural architectures. Use for reasoning about formal knowledge structures, rule-based systems, logic programming, semantic web technologies, and their integration with neural approaches in knowledge graphs and structured reasoning pipelines.
- DO NOT USE FOR: formalising the ontology in Lean (use @lean-knowledge-formalization); commonsense reasoning (use @ai-commonsense-reasoning); agentic AI (use @ai-agentic-evolving).
- TRIGGERS: symbolic AI, neuro-symbolic, knowledge representation, KRR, ontology engineering, description logic, hybrid AI.
Workflow
- Identify the integration question: symbolic-only, neural-only, or hybrid; pick the integration pattern (loose / tight / unified) from the body.
- Pick the KRR formalism (description logic, RDF/OWL, conceptual graph, neural-symbolic embedding) that matches the application.
- Apply the formalism; document where neural and symbolic components communicate + their semantic guarantees.
- Hand off: to
@lean-knowledge-formalization for Lean encoding, to @math-graph-knowledge for graph-theoretic foundations, to @lean-zettelkasten.
Recovery & STOP
- STOP if the question is purely commonsense-reasoning — delegate to
@ai-commonsense-reasoning.
- STOP if the question is about causal/deontic logic — delegate to
@ai-causal-deontic.
- STOP if the neural component requires empirical evaluation beyond methodological reasoning — escalate to
@research-council.
Handoffs
- Predecessors:
agent:gateway, skill:lean-research.
- Successors:
skill:lean-knowledge-formalization, skill:ai-commonsense-reasoning, skill:math-graph-knowledge.
Part 1 — Knowledge Representation Foundations
1.1 Representation Languages
| Language |
Expressiveness |
Decidability |
Common relevance |
| Propositional logic |
Low |
P (SAT: NP-complete) |
Gate predicates and finite checks |
| First-order logic (FOL) |
High |
Semi-decidable |
Theorem formalization |
| Description logic (ALC) |
Medium |
ExpTime |
Ontology TBoxes |
| OWL-DL |
Medium-high |
2NExpTime |
Semantic web ontologies |
| Datalog |
Limited FOL |
P (data complexity) |
Recursive queries on knowledge graphs |
| Answer Set Programming |
Nonmonotonic |
ΣP2-complete |
Default reasoning |
| Modal logic |
FOL + modalities |
Varies |
Epistemic/deontic reasoning |
1.2 Ontology Engineering
Foundational ontologies:
- DOLCE (Descriptive Ontology for Linguistic and Cognitive Engineering)
- BFO (Basic Formal Ontology) — ISO 21838
- SUMO (Suggested Upper Merged Ontology)
Design patterns:
- Parthood and mereology
- Temporal entities (endurants vs perdurants)
- Roles and role-playing
- Quality and quality spaces
Common application: knowledge-graph quality gates validate ontological consistency:
- TBox coherence (no unsatisfiable concepts)
- ABox consistency (instances satisfy TBox constraints)
- Schema-instance alignment
1.3 Formal Reasoning Systems
| System |
Approach |
Completeness |
Use |
| Tableaux |
Model construction attempt |
Complete for DL |
Ontology reasoning |
| Resolution |
Refutation |
Complete for FOL |
Theorem proving |
| Sequent calculus |
Structural proof |
Complete for FOL |
Proof theory |
| Natural deduction |
Introduction/elimination |
Complete for FOL |
Human-like proofs |
| Type theory |
Curry-Howard |
??? (depends on system) |
Lean 4 foundation |
Part 2 — Neuro-Symbolic Integration
2.1 Integration Spectrum (Kautz 2020)
| Level |
Description |
Example |
Pipeline role |
| 1 |
Symbolic ← Neural |
Neural generates symbolic output |
Experience → symbols |
| 2 |
Symbolic → Neural |
Symbolic knowledge guides neural |
Structuring → embedding |
| 3 |
Hybrid pipeline |
Neural + symbolic sequential |
Full Project pipeline |
| 4 |
Tightly coupled |
Neural and symbolic share representation |
Graph of Thoughts |
| 5 |
Unified |
Single system with both capabilities |
Target architecture |
2.2 Key Architectures
- Neural theorem proving: Neural guide for tactic selection (GPT-f, AlphaProof)
- Knowledge graph embeddings: TransE, RotatE, CompGCN — vector representations of KG
- Graph neural networks: Message passing on knowledge structures
- Neurosymbolic concept learner: Learn visual concepts as logical programs
- Logic tensor networks: Differentiable first-order logic
2.3 Typical Neuro-Symbolic Position
Many verification-oriented pipelines operate at Level 3-4:
- Ingest phase: neural perception, extraction, or embedding.
- Articulation: neural-to-symbolic conversion from natural language to structured claims.
- Structuring: symbolic knowledge graph construction and validation.
- Consolidation: hybrid formal verification plus neural synthesis.
- Application: symbolic-to-neural feedback from validated knowledge to new tasks.
Part 3 — Commonsense Reasoning
3.1 Commonsense Knowledge Types
| Type |
Description |
Formalization Challenge |
| Physical |
Objects fall, liquids flow |
Qualitative physics, spatial reasoning |
| Social |
People have intentions, emotions |
Theory of mind, folk psychology |
| Temporal |
Events have duration, causation |
Allen's interval algebra |
| Taxonomic |
Dogs are animals |
Inheritance hierarchies |
| Default |
Birds fly (unless penguin) |
Nonmonotonic logic |
| Causal |
Pushing causes movement |
Causal models (Pearl) |
3.2 Formal Approaches
- Circumscription (McCarthy): Minimize abnormality
- Default logic (Reiter): Default rules with exceptions
- Answer set programming: Stable models with negation-as-failure
- Probabilistic logic: Weight rules by confidence
- Large language models: Implicit commonsense from training data
3.3 Pipeline Integration
Commonsense reasoning commonly enters structured-AI pipelines in:
- Articulation: Interpreting tacit knowledge requires commonsense context
- Structuring: Default rules for knowledge graph completion
- Quality gates: Commonsense consistency checks on extracted knowledge
- Trust dynamics: Social commonsense for multi-agent coordination
Part 4 — Knowledge Graph Reasoning
4.1 Reasoning Tasks
| Task |
Input |
Output |
Method |
| Link prediction |
$(h, r, ?)$ |
Missing tail entity |
Embedding + scoring |
| Type inference |
Entity features |
Entity type |
Classification |
| Rule mining |
KG triples |
Horn rules |
AMIE, AnyBURL |
| Query answering |
Complex query |
Answer entities |
Query embedding |
| KG completion |
Partial KG |
Complete KG |
Combination methods |
| Consistency checking |
KG + constraints |
Violations |
DL reasoning |
4.2 Formal Quality Metrics
| Metric |
Formula |
Interpretation |
| Precision |
TP / (TP + FP) |
Fraction of predicted links that are correct |
| Recall |
TP / (TP + FN) |
Fraction of true links predicted |
| MRR |
$\frac{1}{ |
Q |
| Hits@K |
Fraction of correct in top-K |
Retrieval quality |
| Semantic validity |
Ontology-consistency rate |
Structural soundness |
4.3 Knowledge Graph Architecture
Experience → Raw triples (LLM extraction)
→ Articulation → Candidate assertions with confidence
→ Structuring → Validated KG with ontological constraints
→ Consolidation → Proven properties (Lean formalization)
→ Innovation → Novel inferences from verified base
Quality gates at each transition enforce:
- Confidence thresholds (configurable per domain)
- Ontological consistency (TBox reasoning)
- Provenance tracking (W3C PROV-O)
- Temporal validity (assertions expire)
Part 5 — Host-Repository Lean Extension Points
Do not assume repository-local Lean modules, tactics, or namespaces exist unless the host repository explicitly provides them. When a repository has local knowledge-graph or quality-gate modules, map them to this generic checklist:
| Local extension point |
Symbolic AI aspect |
Typical structures |
| Provenance / audit trail module |
DAG well-formedness, trust composition |
stages, edges, well-formedness predicates |
| Causal / knowledge-graph module |
Causal DAG and graph formalization |
causal links, typed edges, confidence scores |
| Quality-gate module |
Predicate logic on quality measures |
gates, thresholds, monotonicity theorems |
| Classification / regime module |
Decision procedures for regimes |
regime types, decidability, monotonicity |
| Causal-reasoning skill handoff |
Causal DAGs and counterfactual reasoning |
delegate to @lean-causal-reasoning |
Part 6 — Research Connections
6.1 Epistemic Mapping Targets
| KK (Known) |
KU (Gap) |
UU (To Discover) |
| DAG formalization |
Full DL reasoning in Lean |
OWL-to-Lean translation |
| Propositional gates |
Nonmonotonic formalization |
Commonsense integration |
| Trust composition |
Neuro-symbolic verification |
LLM-generated proof verification |
| Provenance chains |
Temporal knowledge evolution |
Ontology evolution formalization |
6.2 Key References
- Brachman & Levesque (2004) — Knowledge Representation and Reasoning
- Hitzler et al. (2020) — Neuro-Symbolic AI: state of the art
- Marcus & Davis (2019) — Rebooting AI (commonsense perspective)
- Hogan et al. (2021) — Knowledge Graphs (comprehensive survey)
- Davis (2015) — Commonsense reasoning: an event calculus perspective
1---2name: ai-symbolic-neuro3description: USE FOR: Symbolic AI, neuro-symbolic integration, knowledge representation and reasoning (KRR), ontology engineering, description logics, and hybrid symbolic-neural architectures. Use for reasoning about formal knowledge structures, rule-based systems, logic programming, semantic web technologies, and their integration with neural approaches in knowledge graphs and structured reasoning pipelines. DO NOT USE FOR: formalising the ontology in Lean (use @lean-knowledge-formalization); commonsense reasoning (use @ai-commonsense-reasoning); agentic AI (use @ai-agentic-evolving). TRIGGERS: symbolic AI, neuro-symbolic, knowledge representation, KRR, ontology engineering, description logic, hybrid AI.4---567# Symbolic AI & Neuro-Symbolic Integration89Formal knowledge representation, symbolic reasoning, and their integration with neural methods for knowledge structuring and consolidation pipelines.1011---1213## Routing1415- **USE FOR:** Symbolic AI, neuro-symbolic integration, knowledge representation and reasoning (KRR), ontology engineering, description logics, and hybrid symbolic-neural architectures. Use for reasoning about formal knowledge structures, rule-based systems, logic programming, semantic web technologies, and their integration with neural approaches in knowledge graphs and structured reasoning pipelines.16- **DO NOT USE FOR:** formalising the ontology in Lean (use @lean-knowledge-formalization); commonsense reasoning (use @ai-commonsense-reasoning); agentic AI (use @ai-agentic-evolving).17- **TRIGGERS:** symbolic AI, neuro-symbolic, knowledge representation, KRR, ontology engineering, description logic, hybrid AI.1819## Workflow20211. Identify the integration question: symbolic-only, neural-only, or hybrid; pick the integration pattern (loose / tight / unified) from the body.222. Pick the KRR formalism (description logic, RDF/OWL, conceptual graph, neural-symbolic embedding) that matches the application.233. Apply the formalism; document where neural and symbolic components communicate + their semantic guarantees.244. Hand off: to `@lean-knowledge-formalization` for Lean encoding, to `@math-graph-knowledge` for graph-theoretic foundations, to `@lean-zettelkasten`.2526## Recovery & STOP2728- STOP if the question is purely commonsense-reasoning — delegate to `@ai-commonsense-reasoning`.29- STOP if the question is about causal/deontic logic — delegate to `@ai-causal-deontic`.30- STOP if the neural component requires empirical evaluation beyond methodological reasoning — escalate to `@research-council`.3132## Handoffs3334- **Predecessors:** `agent:gateway`, `skill:lean-research`.35- **Successors:** `skill:lean-knowledge-formalization`, `skill:ai-commonsense-reasoning`, `skill:math-graph-knowledge`.3637---3839## Part 1 — Knowledge Representation Foundations4041### 1.1 Representation Languages4243| Language | Expressiveness | Decidability | Common relevance |44|---|---|---|---|45| Propositional logic | Low | P (SAT: NP-complete) | Gate predicates and finite checks |46| First-order logic (FOL) | High | Semi-decidable | Theorem formalization |47| Description logic (ALC) | Medium | ExpTime | Ontology TBoxes |48| OWL-DL | Medium-high | 2NExpTime | Semantic web ontologies |49| Datalog | Limited FOL | P (data complexity) | Recursive queries on knowledge graphs |50| Answer Set Programming | Nonmonotonic | ΣP2-complete | Default reasoning |51| Modal logic | FOL + modalities | Varies | Epistemic/deontic reasoning |5253### 1.2 Ontology Engineering5455**Foundational ontologies:**56- DOLCE (Descriptive Ontology for Linguistic and Cognitive Engineering)57- BFO (Basic Formal Ontology) — ISO 2183858- SUMO (Suggested Upper Merged Ontology)5960**Design patterns:**61- Parthood and mereology62- Temporal entities (endurants vs perdurants)63- Roles and role-playing64- Quality and quality spaces6566**Common application:** knowledge-graph quality gates validate ontological consistency:67- TBox coherence (no unsatisfiable concepts)68- ABox consistency (instances satisfy TBox constraints)69- Schema-instance alignment7071### 1.3 Formal Reasoning Systems7273| System | Approach | Completeness | Use |74|---|---|---|---|75| Tableaux | Model construction attempt | Complete for DL | Ontology reasoning |76| Resolution | Refutation | Complete for FOL | Theorem proving |77| Sequent calculus | Structural proof | Complete for FOL | Proof theory |78| Natural deduction | Introduction/elimination | Complete for FOL | Human-like proofs |79| Type theory | Curry-Howard | ??? (depends on system) | Lean 4 foundation |8081---8283## Part 2 — Neuro-Symbolic Integration8485### 2.1 Integration Spectrum (Kautz 2020)8687| Level | Description | Example | Pipeline role |88|---|---|---|---|89| 1 | Symbolic ← Neural | Neural generates symbolic output | Experience → symbols |90| 2 | Symbolic → Neural | Symbolic knowledge guides neural | Structuring → embedding |91| 3 | Hybrid pipeline | Neural + symbolic sequential | Full Project pipeline |92| 4 | Tightly coupled | Neural and symbolic share representation | Graph of Thoughts |93| 5 | Unified | Single system with both capabilities | Target architecture |9495### 2.2 Key Architectures9697- **Neural theorem proving**: Neural guide for tactic selection (GPT-f, AlphaProof)98- **Knowledge graph embeddings**: TransE, RotatE, CompGCN — vector representations of KG99- **Graph neural networks**: Message passing on knowledge structures100- **Neurosymbolic concept learner**: Learn visual concepts as logical programs101- **Logic tensor networks**: Differentiable first-order logic102103### 2.3 Typical Neuro-Symbolic Position104105Many verification-oriented pipelines operate at Level 3-4:106- **Ingest phase**: neural perception, extraction, or embedding.107- **Articulation**: neural-to-symbolic conversion from natural language to structured claims.108- **Structuring**: symbolic knowledge graph construction and validation.109- **Consolidation**: hybrid formal verification plus neural synthesis.110- **Application**: symbolic-to-neural feedback from validated knowledge to new tasks.111112---113114## Part 3 — Commonsense Reasoning115116### 3.1 Commonsense Knowledge Types117118| Type | Description | Formalization Challenge |119|---|---|---|120| Physical | Objects fall, liquids flow | Qualitative physics, spatial reasoning |121| Social | People have intentions, emotions | Theory of mind, folk psychology |122| Temporal | Events have duration, causation | Allen's interval algebra |123| Taxonomic | Dogs are animals | Inheritance hierarchies |124| Default | Birds fly (unless penguin) | Nonmonotonic logic |125| Causal | Pushing causes movement | Causal models (Pearl) |126127### 3.2 Formal Approaches128129- **Circumscription** (McCarthy): Minimize abnormality130- **Default logic** (Reiter): Default rules with exceptions131- **Answer set programming**: Stable models with negation-as-failure132- **Probabilistic logic**: Weight rules by confidence133- **Large language models**: Implicit commonsense from training data134135### 3.3 Pipeline Integration136137Commonsense reasoning commonly enters structured-AI pipelines in:138- **Articulation**: Interpreting tacit knowledge requires commonsense context139- **Structuring**: Default rules for knowledge graph completion140- **Quality gates**: Commonsense consistency checks on extracted knowledge141- **Trust dynamics**: Social commonsense for multi-agent coordination142143---144145## Part 4 — Knowledge Graph Reasoning146147### 4.1 Reasoning Tasks148149| Task | Input | Output | Method |150|---|---|---|---|151| Link prediction | $(h, r, ?)$ | Missing tail entity | Embedding + scoring |152| Type inference | Entity features | Entity type | Classification |153| Rule mining | KG triples | Horn rules | AMIE, AnyBURL |154| Query answering | Complex query | Answer entities | Query embedding |155| KG completion | Partial KG | Complete KG | Combination methods |156| Consistency checking | KG + constraints | Violations | DL reasoning |157158### 4.2 Formal Quality Metrics159160| Metric | Formula | Interpretation |161|---|---|---|162| Precision | TP / (TP + FP) | Fraction of predicted links that are correct |163| Recall | TP / (TP + FN) | Fraction of true links predicted |164| MRR | $\frac{1}{|Q|}\sum_{q \in Q} \frac{1}{\text{rank}_q}$ | Mean reciprocal rank of correct answers |165| Hits@K | Fraction of correct in top-K | Retrieval quality |166| Semantic validity | Ontology-consistency rate | Structural soundness |167168### 4.3 Knowledge Graph Architecture169170```171Experience → Raw triples (LLM extraction)172 → Articulation → Candidate assertions with confidence173 → Structuring → Validated KG with ontological constraints174 → Consolidation → Proven properties (Lean formalization)175 → Innovation → Novel inferences from verified base176```177178Quality gates at each transition enforce:179- Confidence thresholds (configurable per domain)180- Ontological consistency (TBox reasoning)181- Provenance tracking (W3C PROV-O)182- Temporal validity (assertions expire)183184---185186## Part 5 — Host-Repository Lean Extension Points187188Do not assume repository-local Lean modules, tactics, or namespaces exist unless the host repository explicitly provides them. When a repository has local knowledge-graph or quality-gate modules, map them to this generic checklist:189190| Local extension point | Symbolic AI aspect | Typical structures |191|---|---|---|192| Provenance / audit trail module | DAG well-formedness, trust composition | stages, edges, well-formedness predicates |193| Causal / knowledge-graph module | Causal DAG and graph formalization | causal links, typed edges, confidence scores |194| Quality-gate module | Predicate logic on quality measures | gates, thresholds, monotonicity theorems |195| Classification / regime module | Decision procedures for regimes | regime types, decidability, monotonicity |196| Causal-reasoning skill handoff | Causal DAGs and counterfactual reasoning | delegate to `@lean-causal-reasoning` |197198---199200## Part 6 — Research Connections201202### 6.1 Epistemic Mapping Targets203204| KK (Known) | KU (Gap) | UU (To Discover) |205|---|---|---|206| DAG formalization | Full DL reasoning in Lean | OWL-to-Lean translation |207| Propositional gates | Nonmonotonic formalization | Commonsense integration |208| Trust composition | Neuro-symbolic verification | LLM-generated proof verification |209| Provenance chains | Temporal knowledge evolution | Ontology evolution formalization |210211### 6.2 Key References212213- Brachman & Levesque (2004) — Knowledge Representation and Reasoning214- Hitzler et al. (2020) — Neuro-Symbolic AI: state of the art215- Marcus & Davis (2019) — Rebooting AI (commonsense perspective)216- Hogan et al. (2021) — Knowledge Graphs (comprehensive survey)217- Davis (2015) — Commonsense reasoning: an event calculus perspective