KELE Inference Engine

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KELE is a forward-chaining inference engine based on Assertion Logic, implementing a subset of the logic.

It supports term-level facts, nested terms, equivalence axioms, and operators with functions, and integrates well with modern Python (3.13+). You can embed your tools through operator implementations (and embed KELE into your tools), while we leave the burden of wrapping/binding other languages to developers rather than users.

⚠️ Project status
We released the first alpha version on 12/31 and will move it to a beta release as soon as possible after the holiday. The engine will maintain backward compatibility for commonly used public classes and modules, while internal components are still evolving and under active development.

✨ Features

• Term-level facts and reasoning: term-centric organization and inference, suited for equality knowledge
• Equivalence axioms: convenient equivalence expressions with internal maintenance
• Nested compound terms: operators can nest to build complex structures
• Implement functions for operators: implement functions for operators (e.g., arithmetic, equation solving)

Implement functions for operators ≈ Prolog meta-predicates / ASP HEX external predicates (not identical semantics, similar usage).

🔍 Matching semantics

• Loose matching: treat subsumption as "intersection" matching, without input/constraint distinction
• Concept overlap check: returns whether there is a non-empty common concept set aligned
• Mismatch handling: incompatible

🔧 Installation

Option A: PyPI (after release)

You can grab the latest built wheel from GitHub Actions or install a published release directly.

pip install kele

Option B: Build from source

Requirements: Python 3.13+; Rust toolchain (rustup); on Windows, MSVC (Visual Studio Build Tools).

git clone https://github.com/USTC-KnowledgeComputingLab/KELE
cd KELE
uv sync
uv run maturin develop --skip-install  # install rust and MSVC (Windows) beforehand

🚀 Quick start

Full example: examples/relationship_quick_start.py

uv run python examples/relationship_quick_start.py
# Output: grandparent relation inference result (forward-chaining demo)

🧩 Core syntax at a glance

Type	Meaning	Example/Hint
Concept	Group of objects sharing something in common	Person = Concept("Person")
Constant	Object (belongs to concepts)	alice = Constant("Alice", Person)
Variable	Placeholder in rules/queries	X = Variable("X")
Operator	Map a tuple of objects into a single one	parent(Person, Person) -> Bool
CompoundTerm	Operator + arguments	CompoundTerm(parent, [alice, bob])
Assertion	“term = term” assertion	Assertion(..., ...)
Formula	Combine assertions with AND/OR/…	Formula(A, "AND", B)
Rule	body → head	Rule(head=..., body=...)
QueryStructure	Query input (premises + question)	QueryStructure(premises=[...], question=[...])
InferenceEngine	Engine core	InferenceEngine(facts=[...], rules=[...])

examples/relationship_quick_start.py shows a family-relation inference example, illustrating how the pieces fit together:

1. Define concepts (Concept) and operators (Operator), such as Person, parent, grandparent.
2. Add initial facts (Assertion), e.g. “Bob is Alice’s parent”.
3. Write rules (Rule + Formula), e.g. “if parent(X, Y) and parent(Y, Z), then grandparent(X, Z)”.
4. Build a query (QueryStructure) and run InferenceEngine.

Example snippet (imports/details omitted; see examples/relationship_quick_start.py for a runnable version):

# 1. Define concepts and operators
Person = Concept("Person")
...

# 2. Add facts
alice = Constant("Alice", Person)
...

facts = [
    # parent(Alice, Bob) = True
    Assertion(CompoundTerm(parent, [alice, bob]), true_const),
    ...
]

# 3. Define rules + query
rules = [Rule(
    head=...,
    body=...,
)]

engine = InferenceEngine(facts=facts, rules=rules)
query = QueryStructure(premises=facts, question=[...])  # e.g., ask for grandparent(Alice, X)

print(engine.infer_query(query))

🧭 Documentation

• Sphinx docs:

  • Read the Docs: WIP
  • Build locally: uv run sphinx-build -b html docs\source docs\build\html

• Tutorial: https://msg-bq.github.io/

🗺️ Roadmap

WIP

🤝 Contributing

Issues/PRs welcome! Please read CONTRIBUTING.md, and consider enabling ruff and mypy.

If you have any questions about using the engine—including usage, syntax/semantics, or theoretical foundations—please open an issue or contact us.

🪪 License

This project uses the BSD 3-Clause license. See LICENSE.