[SystemSafety] Difference between software reliability and astrology

[Prof. Dr. Peter Bernard Ladkin]

On 2024-08-13 15:26 , Paul Sherwood wrote:
> Peter,
>
> I remain somewhat confused, here.
>
> On 2024-08-13 13:57, Prof. Dr. Peter Bernard Ladkin wrote:
>> If you reject the statistical processes that are generally recognised to model software behaviour,
>
> Which statistical processes are generally recognised to model software behaviour?

We are talking safety-critical software.

The answer is memoryless processes. "Memoryless" here is a technical term of statistics. 
https://mathworld.wolfram.com/Memoryless.html  It should not be thought to have much if anything to 
do with "computer memory". Some of us have had years-long "discussions" with engineers who were 
convinced it must have somehow to do with it, somehow.

Not all software is used in a manner which can be claimed to be memoryless. It obviously needs to be 
so used if you are going to model it with memoryless processes.

> From previous discussions here and elsewhere (and prior consideration of ISO26262) I was under the 
> impression that software is 'generally recognised' to be (ideally) deterministic?

Did you read the note I forwarded?

PBL

Prof. Dr. Peter Bernard Ladkin
Causalis Limited/Causalis IngenieurGmbH, Bielefeld, Germany
Tel: +49 (0)521 3 29 31 00