EYE
The original Euler Yet another proof Engine: a mature N3 and RDF Surfaces reasoner with proof output.
Notation3 reasoners
The EYE family offers several Notation3 implementations and runtimes. Choose the one that best matches your environment, integration needs, and reasoning workload.
eye-js
The original EYE engine compiled to WebAssembly and packaged for browser and Node.js applications.
Eyeling
A compact N3 reasoner for Node.js, browsers, RDF pipelines, streaming messages, and accountable proofs.
Pyling
A Python port of Eyeling for N3 reasoning from Python code, notebooks, RDFLib graphs, or the command line.
Eyeron
A Rust N3 reasoner that derives conclusions, writes N3 proofs, and checks them, as a CLI, library, or browser app.
Romeo
A fast, dependency-free forward-chaining N3 reasoner descended from Eyeling and distributed as a static binary.
Rule languages with checkable proofs
A newer generation of EYE engines works with Prolog-style facts and rules or with SPARQL. They share one bargain: an answer can come with the reasoning behind it, and a separate checker can verify that proof against the program.
EyeProlog
Turns portable ISO Prolog programs into answers and inspectable proofs, with automatic tabling and RDF 1.2 interchange. Documented in The Art of EyeProlog.
eyeon
A symbolic logic programming language in a subset of Prolog, with query explanations, executable checks, and independently checked proof certificates.
Eyedia
Reasoning you can see: a dependency-free Prolog rule language that combines forward :+ and backward :- rules with checkable proofs.
peye
A standalone, dependency-free Python rule language with forward and backward reasoning, checkable proofs, and a conformance suite.
wheye
A small relational reasoner: a Prolog subset with tabled recursion and independently checked proof certificates.
Eyeleng
An implementation of SPARQL 1.2 RL (SRL) tracking the W3C draft, with stratification, forward and backward evaluation, and a conformance harness.
Try one in your browser
These hosted playgrounds let you edit and run examples without installing a local reasoner.
eye-js example
Run the original EYE reasoner in a browser.
Eyeling playground
Experiment with the compact JavaScript engine.
Eyeron playground
Reason with the Rust implementation through WebAssembly.
Eyeleng playground
Run SRL rule sets over RDF 1.2 data in the browser.
EyeProlog playground
Run portable Prolog programs with inspectable proofs.
eyeon playground
Ask, explain with why, and check assertions.
Eyedia playground
See derivations and verify their proof certificates.
peye playground
Write Python rules and run the conformance suite in the browser.
wheye playground
Try tabled recursion and checked proof certificates.
eyelee playground
Evaluate Dutch-law questions with Answer, Reason, and Check.
A shared starting point
Almost every engine can begin with the same familiar Socrates example: facts and a rule go in; a conclusion comes out, together with the reasoning that supports it.
human(socrates).
mortal(Person) :- human(Person).
?- mortal(Who).
?- why.@prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#>.
@prefix : <http://example.org/socrates#>.
:Socrates a :Human.
:Human rdfs:subClassOf :Mortal.
{ ?S a ?A. ?A rdfs:subClassOf ?B }
=>
{ ?S a ?B }.Wider EYE ecosystem
These close neighbours build on the reasoners above: drivers, applications, interchange tools, and test suites.
- eyelet — EYE reasoning in portable Prolog with
:+bottom-up rules - eyelee — law execution engine with Answer, Reason, and Check
- rdf-prolog-interchange — reversible RDF 1.2 ↔ ISO Prolog
rdf/4facts - Koreografeye — web choreography service using EYE
- lingua — RDF/TriG graph rules
- rdfsurfaces-tests — RDF Surfaces test kit
- Notation3-By-Example — practical N3 examples
Looking for the broader reasoner landscape? Jos De Roo maintains an overview spanning N3, RDF Surfaces, Datalog, SHACL Rules, RIF, and first-order logic: view the full reasoners list.