The Selmo attitude

1.3 The Selmo Attitude

The Selmo attitude is not a technology decision and not a tool promise.

It is a conscious response to the problems of modern machine logic: implicit logic, lack of traceability and non-tenable responsibility.

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Model before code

In Selmo the code is not the starting point.

The code is:

• an implementation

• a derivation

• a result

The model, on the other hand, is:

• the formal description of behavior

• the single source of truth

• independent of programming language and platform

What is not modeled does not exist.

This attitude enforces:

• explicit states

• clear expectations

• defined reactions

The code follows the model – not the other way around.

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Determinism

Selmo assumes that machine behavior must be unambiguous at every moment.

This means:

• the machine is always in a clearly defined state

• expectations are explicitly described

• reactions to deviations are specified

There are:

• no implicit transitions

• no “good enough” states

• no context-dependent interpretation

Same state + same conditions always lead to the same behavior.

Determinism is not a limitation, but the prerequisite for:

• Safety

• Automation

• Scalability

• Analyzability

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Responsibility & Transparency

As complexity increases, responsibility also increases:

• for safety

• for availability

• for liability

• for traceability

Selmo consciously accepts this responsibility.

Through the formal model it is always traceable:

• which state is active

• which expectations apply

• why a reaction occurs

• why a movement is allowed or prevented

Transparency does not arise from comments, but from modeled meaning.

What is explainable is verifiable. What is verifiable is accountable.

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Consequence of the attitude

The Selmo attitude leads to clear consequences:

• Machine logic becomes explicit

• Diagnosis arises automatically

• Documentation is consistent

• Changes are controllable

• Responsibility is justifiable

This attitude is non-negotiable, because it forms the foundation of all further concepts.

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Transition to the model

The Selmo attitude answers the Why.

The following chapters answer the How:

• how machines are structured

• how behavior is modeled

• how operation, safety and diagnosis arise from it

First the attitude, then the model.