Double Entry is Lying to You

You've been told that double entry accounting keeps your finances safe.

That belief is a lie.

The supposed protections of double entry don't prevent disaster; it conceals it. At its core it works on the premise that as long as everything sums to up to zero that everything is fine. The thing no one tells you is that your books can balance to zero while you lose everything you have.

The strict reliance on mathematical checks ignores determinism, permits manipulation, and purposely has no real controls.

We'll uncover:
* The seductive illusion of zero sums
* How a failing business can have balanced books
* How these flaws can hide fraud and crime
* Why double entry can't be patched or "fixed"
* Why AI can compound these problems

You'll leave questioning the fundamental truths behind accounting and ledgering as well as a brief glimpse into what a brighter future could be.

The Mirage of Financial AI: Tracing Truth in an Untraceable System

Thesis: Using AI with financial systems is a ticking time bomb

LLM's are revolutionizing a lot of things about our lives. There are dozen of companies offering AI agents that will interpret your financial data for you. Given you hive level summaries, forecast, charts whatever you want.

But it's all a lie.

The underlying data that powers the worlds financial systems is modeled using double-entry ledgering, which is fundamentally non-deterministic. When you layer the non-determinism of an LLM on top of that you magnify error margins to the point where the result can be completely disconnected from the truth. While all LLMs deal with hallucinations the nature of the underlying system makes it impossible provide sources or traceability follow LLM decisions back to their core proof.

Participants will learn:
- The basics of double entry ledger
- Why double entry is non-deterministic
- How layering non-determinism magnifies errors
- Why hallucinations are even more problematic in this paradigm
- How can we make it better?

Making Impossible States Impossible

A mantra of functionally complete languages in this session we'll explore how to apply these concepts incrementally to your existing TypeScript code bases. We'll demonstrate how to use types to enforce the business rules of a retail application.

We'll explore:
* Enforcing runtime state at compile time
* Type guards
* Why you be confident in your checks

Includes a live coding demonstration that works best with a large screen with good contrast and passable resolution.

Cucumber in the Wild

Overview of a TypeScript code base built from the ground up using Cucumber as the only testing method in a production financial application. We'll discuss what we've found to be amazing, and where we've found rough edges.

Major Topics:
* Behavioral testing
* Test composition
* Where unit testing fits in

This presentation presents code live and requires a decent sized monitor would reasonable contrast and resolution.