Invariants


The rules governing execution in ULM-PD Engine.

Invariants are immutable laws

They don’t persuade, They don’t motivate, They don’t care who believes them They simply define what can and cannot occur, and what happens when thresholds are crossed. Systems that align behaviour to invariants can degrade gracefully. Systems that align behaviour to narrative tend to overshoot, then collapse.and they come in three types

Invariant-first rule

If a mathematical or physical state is valid, it must be representable. Failure to represent a valid state is a system error, not a refusal condition.


Formal systems are not natural laws

Formal systems are built from man-made rules used to describe, organise, and coordinate behaviour. They include systems such as mathematics, logic, programming languages, accounting systems, legal frameworks, money, gender roles, and status.

These systems rely on defined symbols and active execution. Without people or machines enforcing their rules, they do nothing.

Invariants are different. They exist regardless of language, agreement, or belief. They cannot be negotiated, suspended, or redefined.

Formal systems can model aspects of reality, but they are not reality itself. When a formal rule conflicts with a natural constraint, the natural constraint always wins.

Many large-scale human systems operate as if their rules were natural laws. They are not. They persist only because behaviour is coordinated around them.

Invariants exist to prevent this confusion. They enforce the difference between what can be symbolically declared and what can actually occur.


Boundaries are data

Terminal states such as identity elements, limits, fixed points, and finite exhaustion are returned explicitly as data.

Refusal semantics

Refusal occurs only when an invariant is undefined or violated. No other meaning is attached to refusal.


Examples of invariants

Division by zero (impossibility, not ambiguity)

Division requires a non-zero divisor.

The statement “division by zero is undefined” describes a limitation of notation, not the truth of the invariant.

The invariant truth is simpler: it is impossible to divide something by nothing.

There exists no mathematical state satisfying

a = b × 0
  

for any non-zero a.

Because no valid state exists, execution halts.

This is not a boundary condition and not a missing definition. It is the absence of any lawful result.

Examples of domain-specific invariants:

In all cases, failure is not caused by missing information or ambiguity. It occurs because no lawful result exists under the rules of that domain.


Exactness and approximation

Exact representations are used by default. Approximation is explicit, opt-in, and visible in the execution surface.

Tool pluralism

Internal execution may involve multiple computational substrates. Invariant compliance is the only exposed guarantee.

Determinism

Given identical inputs and declared invariants, ULM-PD Engine produces identical output.

Scope and responsibility

Only explicitly declared capabilities are supported. ULM-PD Engine enforces internal correctness but does not replace professional judgement.