4 ms·

This does not seem very rigorous. Can someone point to a better coverage of this topic?

by dqpb 4y ago

thraxil 4y ago
It's not intended to be rigorous. The context here is that Richard I. Cook, one of the main figures in safety and resilience engineering, who's published many, many papers on these topics died recently. The "How Complex Systems Fail" paper is intended to be a bit pithy and light; more an attempt at summarizing years of wisdom. See: https://www.adaptivecapacitylabs.com/blog/2022/09/12/richard-cook-a-life-in-many-acts/ https://www.adaptivecapacitylabs.com/blog/2022/09/12/richard...
- dqpb 4y ago
  Well, this sounds wrong to me: > Catastrophe requires multiple failures – single point failures are not enough My experience is that a single failure causes a cascade of subsequent failures. This topic is very interesting, but this post is more of a teaser of topics than a real explanation.
  - advisedwang 4y ago
    Places where a single failure in an otherwise perfectly functioning system can cause catastrophic outcomes are relatively easy to identify, relatively easy to argue need to be fixed and relatively easy to fix. As a result mature, complex systems have generally developed safety mechanisms for such issues. Once you have done that you need at least two failures (underlying issue + safety, hot+cold, or two interacting systems). I would suspect that your experience of single modes of failure being present are one of the following * Immature system (e.g. a startup) * One where failure is acceptable and so engineering isn't invested in solving these issues (i.e. the author is talking about disasters that kill people, not causing a few mins of ads not getthing shown) * Extreme organizational dysfunction (talking criminal negligence type stuff)
    - dqpb 4y ago
      > Once you have done that you need at least two failures (underlying issue + safety, hot+cold, or two interacting systems). Ah, I missed the part where he said - except for distributed systems. The thing is, effectively all systems are distributed systems with two or more interacting subsystems. And no, I'm not talking about immature systems or ones where failure is acceptable. Queuing issues, for example, are well known to cause to cascading effects, and are not trivial to identify or solve. Even basic correctness issues can be very difficult to identify if you have a large permutation space and no model checking, and will also cascade.
novixyz 4y ago
I agree. I always thought that late Paul Ciliers' did a great summary on complexity (sorry no online link): "Complexity in a Nutshell: I will not provide a detailed description of complexity here, but only summarise the general characteristics of complex systems as I see them. -Complex systems consist of a large number of elements that in themselves can be simple. - The elements interact dynamically by exchanging energy or information. These interactions are rich. Even if specific elements only interact with a few others, the effects of these interactions are propagated throughout the system. The interactions are nonlinear. - There are many direct and indirect feedback loops. - Complex systems are open systems – they exchange energy or information with their environment – and operate at conditions far from equilibrium. Complex systems have memory, not located at a specific place, but distributed throughout the system. Any complex system thus has a history, and the history is of cardinal importance to the behaviour of the system. - The behaviour of the system is determined by the nature of the interactions, not by what is contained within the components. Since the interactions are rich, dynamic, fed back, and, above all, nonlinear, the behaviour of the system as a whole cannot be predicted from an inspection of its components. The notion of emergence is used to describe this aspect. The presence of emergent properties does not provide an argument against causality, only against deterministic forms of prediction. - Complex systems are adaptive. They can (re)organise their internal structure without the intervention of an external agent. Certain systems may display some of these characteristics more prominently than others. These characteristics are not offered as a definition of complexity, but rather as a general, low-level, qualitative description. If we accept this description (which from the literature on complexity theory appears to be reasonable), we can investigate the implications it would have for social or organisational systems." Ciliers, P. (2016). Critical Complexity Collected Essays, Walter de Gruyter GmbH. 67 Also if you look up any Dave Snowden's video on YT you'll find plenty of useful info.

This does not seem very rigorous. Can someone point to a better coverage of this topic?

by dqpb 4y ago

This does not seem very rigorous. Can someone point to a better coverage of this topic?

It's not intended to be rigorous. The context here is that Richard I. Cook, one of the main figures in safety and resilience engineering, who's published many, many papers on these topics died recently. The "How Complex Systems Fail" paper is intended to be a bit pithy and light; more an attempt at summarizing years of wisdom. See: https://www.adaptivecapacitylabs.com/blog/2022/09/12/richard-cook-a-life-in-many-acts/ https://www.adaptivecapacitylabs.com/blog/2022/09/12/richard...

dqpb 4y ago
Well, this sounds wrong to me: > Catastrophe requires multiple failures – single point failures are not enough My experience is that a single failure causes a cascade of subsequent failures. This topic is very interesting, but this post is more of a teaser of topics than a real explanation.
- advisedwang 4y ago
  Places where a single failure in an otherwise perfectly functioning system can cause catastrophic outcomes are relatively easy to identify, relatively easy to argue need to be fixed and relatively easy to fix. As a result mature, complex systems have generally developed safety mechanisms for such issues. Once you have done that you need at least two failures (underlying issue + safety, hot+cold, or two interacting systems). I would suspect that your experience of single modes of failure being present are one of the following * Immature system (e.g. a startup) * One where failure is acceptable and so engineering isn't invested in solving these issues (i.e. the author is talking about disasters that kill people, not causing a few mins of ads not getthing shown) * Extreme organizational dysfunction (talking criminal negligence type stuff)
  - dqpb 4y ago
    > Once you have done that you need at least two failures (underlying issue + safety, hot+cold, or two interacting systems). Ah, I missed the part where he said - except for distributed systems. The thing is, effectively all systems are distributed systems with two or more interacting subsystems. And no, I'm not talking about immature systems or ones where failure is acceptable. Queuing issues, for example, are well known to cause to cascading effects, and are not trivial to identify or solve. Even basic correctness issues can be very difficult to identify if you have a large permutation space and no model checking, and will also cascade.

novixyz 4y ago

I agree. I always thought that late Paul Ciliers' did a great summary on complexity (sorry no online link): "Complexity in a Nutshell: I will not provide a detailed description of complexity here, but only summarise the general characteristics of complex systems as I see them. -Complex systems consist of a large number of elements that in themselves can be simple. - The elements interact dynamically by exchanging energy or information. These interactions are rich. Even if specific elements only interact with a few others, the effects of these interactions are propagated throughout the system. The interactions are nonlinear. - There are many direct and indirect feedback loops. - Complex systems are open systems – they exchange energy or information with their environment – and operate at conditions far from equilibrium. Complex systems have memory, not located at a specific place, but distributed throughout the system. Any complex system thus has a history, and the history is of cardinal importance to the behaviour of the system. - The behaviour of the system is determined by the nature of the interactions, not by what is contained within the components. Since the interactions are rich, dynamic, fed back, and, above all, nonlinear, the behaviour of the system as a whole cannot be predicted from an inspection of its components. The notion of emergence is used to describe this aspect. The presence of emergent properties does not provide an argument against causality, only against deterministic forms of prediction. - Complex systems are adaptive. They can (re)organise their internal structure without the intervention of an external agent. Certain systems may display some of these characteristics more prominently than others. These characteristics are not offered as a definition of complexity, but rather as a general, low-level, qualitative description. If we accept this description (which from the literature on complexity theory appears to be reasonable), we can investigate the implications it would have for social or organisational systems." Ciliers, P. (2016). Critical Complexity Collected Essays, Walter de Gruyter GmbH. 67 Also if you look up any Dave Snowden's video on YT you'll find plenty of useful info.