The PSE Language

A textbook. Andrej Ristić, Zerava Technologies Inc. · 2 October 2026

The PSE language describes a guard, the protective layer between a user and an AI agent, in a few lines of text. This textbook goes from one line to a complete file: each chapter has an explanation, examples traced step by step, and exercises with solutions.

Try it as you read

The PSE Playground runs the language in your browser: write a guard, hand it a series of steps, and see which rule fired and why. Nothing you type leaves the page.

Chapters

1. 1. Status of this textbook
2. 2. What the language is for
3. 3. Core terms
4. 4. First program
5. 5. Setting lines: relation, source, mode
6. 6. Rules
7. 7. infinity
8. 8. Oscillation and borderline
9. 9. The verdict “unknown”
10. 10. Learning and extensions
11. 11. Commands: check, explain, status
12. 12. What the check rejects
13. 13. Complete examples
14. 14. Exercises
15. 15. Reference
16. 16. What the language does not cover

The PSE language describes a guard, the protective layer between a user and an AI agent, in a few lines of text. This textbook goes from one line to a complete file: each chapter has an explanation, examples traced step by step, and exercises with solutions.

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Copyright Andrej Ristić and Zerava Technologies Inc. All rights reserved. Free to read online; please link here rather than copying.