DMN-Prolog Bidirectional Converter

A Python tool for bidirectional conversion between Prolog code and DMN (Decision Model and Notation) for legal/business rule management.

Overview

This tool enables a powerful workflow for converting legal documents into executable decision logic:

Legal Document → LLM → Prolog → DMN → Review → Deploy (Prolog or DMN)
                         ↑                ↓
                         └────────────────┘
                         (Bidirectional)

Why this approach?

• LLM-Friendly Input: Prolog syntax is simpler and more reliable for LLMs to generate than verbose DMN XML
• Human-Friendly Review: DMN provides visual decision tables that legal/business specialists can review
• Flexible Deployment: Deploy as either Prolog (for Prolog engines) or DMN (for DMN engines)
• Quality Control: Bidirectional conversion ensures consistency and reduces hallucination

Supported Prolog Subset

To ensure DMN compatibility, the converter supports a restricted Prolog subset:

• ✓ Horn clauses only (no negation-as-failure, no cuts)
• ✓ Deterministic rules (single output per input combination)
• ✓ Simple data types (atoms, numbers, strings, booleans)
• ✓ Decision table structure (pattern-matching rules)
• ✓ Limited recursion (≤ 3 levels)
• ✓ FEEL expression compatibility (comparison operators: >=, =<, >, <, ==, \=)

Installation

# Basic installation (conversion only)
pip install dmn-prolog-converter

# With validation support
pip install dmn-prolog-converter[validation]

# With all optional features
pip install dmn-prolog-converter[execution]

See CDMN_INTEGRATION.md for details.

Quick Start

Command Line

After installation, you'll have these commands available:

dmn-prolog          # Main CLI tool with subcommands
prolog2dmn          # Quick shortcut: Prolog → DMN
dmn2prolog          # Quick shortcut: DMN → Prolog
z32dmn              # Quick shortcut: Z3 → DMN
dmn2z3              # Quick shortcut: DMN → Z3

Example usage

# Convert Prolog to DMN
dmn-prolog convert rules.pl rules.dmn

# Convert DMN to Prolog
dmn-prolog convert rules.dmn rules.pl

# Validate DMN
dmn-prolog validate rules.dmn

# Show file info
dmn-prolog info rules.pl
dmn-prolog info rules.smt2

# Quick shortcuts
prolog2dmn input.pl output.dmn
dmn2prolog input.dmn output.pl
z32dmn input.smt2 output.dmn
dmn2z3 input.dmn output.smt2

See CLI_GUIDE.md for complete CLI documentation.

Limitations & Future Work

Current Limitations:

• No support for complex Prolog features (cuts, negation-as-failure, DCGs)
• Limited to decision tables (no decision requirement diagrams)
• No support for DMN business knowledge models or contexts
• Arithmetic expressions are basic

Future Enhancements:

• Support for DMN FEEL functions
• Decision requirement diagram generation
• Semantic validation of business logic
• Integration with LLM for natural language descriptions
• Support for more complex Prolog constructs (via approximation)
• Visual DMN table editor integration

Use Cases

1. Legal Document Automation: Convert legal rules to executable format
2. Business Rule Management: Maintain rules in both technical and business-friendly formats
3. Legacy Migration: Migrate Prolog expert systems to DMN standard
4. LLM-Powered Rule Generation: Let LLMs generate Prolog, convert to DMN for review
5. Dual Deployment: Maintain single source, deploy to both Prolog and DMN engines

Contributing

Contributions welcome! Areas for improvement:

• Additional test cases
• Support for more Prolog patterns
• Enhanced FEEL expression generation
• Documentation improvements

License

MIT License - see LICENSE file for details

References

• DMN 1.3 Specification
• FEEL Language Guide
• Prolog Tutorial
• Lark Parser Documentation