What is CADL?
CADL (Contract Architecture Description Language) is a domain-specific language for formally specifying, verifying, and deploying institutional designs in multi-agent System of Systems (SoS).
CADL adopts a three-layer architecture — Institution, Protocol, and Algorithm — so that governance rules, coordination procedures, and the algorithms each side runs (referred to by name) are described in one language. From a CADL specification, the toolchain checks the design for contradictions and generates code and simulator configurations.
Read the Specification →Get started
The reference implementation is the cadl command-line tool (Python 3.9 or later). Install it from PyPI, fetch the examples, and check one:
All commands are listed in the README of the cadl repository. For a guided walkthrough, take the hands-on course.
Source on GitHubcadl-lang on PyPIpip install cadl-lang git clone https://github.com/ertlnagoya/cadl cadl check cadl/examples/robot_delivery.cadl cadl verify cadl/examples/robot_delivery.cadl
What is CADL Explorer?
CADL Explorer is an interactive web application that demonstrates the CADL governance pipeline end-to-end. Starting from a CADL specification, it traces the full causal chain — from institutional design through simulation configuration to experiment results and governance evaluation.
The tool makes the relationship between design decisions and behavioral outcomes transparent and reproducible, helping researchers explore how governance parameters affect multi-agent system performance.
Try CADL Explorer →Take the Hands-on
SoS-DSL Hands-on is a self-paced workshop of about 95 minutes (or a 5-session exercise course) that walks you through the entire pipeline of the CADL toolchain on a robot delivery System of Systems: CADL modelling → SoS-DSL contracts (lifecycle + monitors) → visualisation → code generation → live simulation.
Materials include a main textbook, a 5-session exercises booklet with graded tasks, and an academic background page covering ISO/IEC/IEEE 21839/40/41 and Maier's criteria.
Open the Hands-on Index →- Main textbook — 6 steps × 15 min
- Exercises — 5-session series with rubric
- Academic background — Maier's 5 criteria, ISO 21839/40/41, references
Key Features
Three-Layer Architecture
Describe institutions (authority, incentives, information sharing), protocols (coordination procedures), and the algorithms each side runs (by name) in a single language.
Formal Verification
Check each contract for contradictions between its assumptions and guarantees with an SMT solver, and detect deadlocks in protocols.
End-to-End Pipeline
Generate code and simulator configurations from CADL specs, and trace the chain from institutional design to behavioral evaluation with a simulator or CADL Explorer.