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Mistaber (מסתבר)

The first formal symbolic reasoning system for computational halacha

"It stands to reason" — A symbolic AI platform that models halachic authority using Kripke semantics, enabling formal analysis of how rulings propagate and diverge across different poskim.

The World Hierarchy

Different halachic authorities (poskim) form an inheritance hierarchy. Child worlds inherit rulings from parents but can override them:

graph TD
    base["base<br/><small>Shulchan Aruch</small>"]

    base --> mechaber["Mechaber<br/><small>Sefardi</small>"]
    base --> rema["Rema<br/><small>Ashkenazi</small>"]
    base --> gra["GRA<br/><small>Vilna Gaon</small>"]

    mechaber --> sefardi_yo["Yalkut Yosef<br/><small>Modern Sefardi</small>"]
    rema --> ashk_mb["Mishnah Berurah<br/><small>Modern Ashkenazi</small>"]
    rema --> ashk_ah["Aruch HaShulchan"]
    gra --> ashk_ah

    style base fill:#4a5568,stroke:#718096,color:#fff
    style mechaber fill:#2d3748,stroke:#4a5568,color:#fff
    style rema fill:#2d3748,stroke:#4a5568,color:#fff
    style gra fill:#2d3748,stroke:#4a5568,color:#fff
    style sefardi_yo fill:#1a202c,stroke:#2d3748,color:#fff
    style ashk_mb fill:#1a202c,stroke:#2d3748,color:#fff
    style ashk_ah fill:#1a202c,stroke:#2d3748,color:#fff

When you query Mistaber, it traverses this graph to derive rulings with full source chains — and detects where authorities disagree.

See It In Action: The Fish & Dairy Dispute

A classic machloket (dispute): Can you eat fish with dairy?

The Mechaber (Shulchan Aruch YD 87:3) forbids it due to health concerns (sakana). The Rema permits it, rejecting the health argument. Let's query both:

mistaber compare "holds(status(fish_dairy, X), W)" --worlds mechaber,rema

from mistaber.engine import HsrsEngine

engine = HsrsEngine("./mistaber/ontology")
dispute = engine.detect_machloket("status(fish_dairy, X)")

for world, ruling in dispute.items():
    print(f"{world}: {ruling}")

mechaber: forbidden (sakana)
rema:     permitted
gra:      permitted (follows Rema)
ashk_mb:  permitted (follows Rema)
sefardi:  forbidden (follows Mechaber)

What just happened?

  1. Mistaber loaded rulings from 7 halachic authorities
  2. It detected a machloket between Mechaber and Rema
  3. It traced how modern poskim (M.B., Yalkut Yosef) inherit their positions
  4. Every ruling links back to sources in Shulchan Aruch

Scientific Contributions

Mistaber introduces eight novel contributions to computational law and symbolic AI:

  • Kripke Semantics for Halacha

    First application of possible-world semantics to model halachic authority variation

  • Deontic Logic Extensions

    Halacha-specific operators: madrega levels, safek resolution, context modifiers

  • Formal Upper Ontology

    69 predicates, 29 sorts — rigorous type system for halachic concepts

  • Multi-World Inheritance

    DAG-based authority chains with override semantics

  • Safek Calculus

    Formal doubt propagation: ספק דאורייתא לחומרא, ספק דרבנן לקולא

  • Provenance Chains

    Every ruling traceable to Shulchan Aruch → Tur → Rambam → Gemara

Read the Paper Scientific Details

Explore the Documentation

  • Getting Started

    Install Mistaber and run your first query in 5 minutes.

    Perfect for: Developers, Researchers

    Installation Guide

  • Tutorials

    Learn to encode halachic rules, model disputes, and extend the ontology.

    Perfect for: All users

    Start Learning

  • Reference

    CLI commands, Python API, HLL syntax, and predicate registry.

    Perfect for: Developers

    API Reference

  • Formal Foundations

    Modal logic, deontic operators, Kripke frames, and formal proofs.

    Perfect for: Researchers, Scholars

    Deep Dive

  • Encode Halacha

    Contribute to the ontology using our AI-assisted encoding workflow with the mistaber-skills plugin.

    Perfect for: Contributors, Scholars

    Start Encoding

  • Plugin Documentation

    Complete guide to the mistaber-skills Claude Code plugin: skills, hooks, and agents.

    Perfect for: Contributors, Developers

    Plugin Guide

Important: Not a Posek

Mistaber is a research tool for analyzing the formal structure of halachic reasoning. It is not a substitute for consulting a qualified rabbi. Always seek proper halachic guidance for practical questions.

Ready to Start?

pip install mistaber
mistaber --help

Installation Guide View on GitHub

Get Involved

  • Star us on GitHub
  • Report issues or request features
  • Contribute to the ontology
  • Contact: levi@brainyblaze.com

Contributing Guide