Re: Reliability and assurances

[Mario Obejas <obejas@phylum.rsc.raytheon.com>]

Mark R. Lindsey wrote:
>I'm working on a theory: if (A) you can't be assured that a subsystem is going
>to work all of the time, then (B) you can't be assured that a subsystem is
>going to work any of the time.
>
>Does that seem reasonable?

Not to me. Maybe you wrote it different than what you intended, 
e.g., you meant "system" instead of subsystem in your B clause.
IMHO, your A and B clauses need to be switched.
Let's substitute numerical values:
all=100%
any="<100%"

I'd agree with
(B) If 
  one "can't be assured that a subsystem is going to work <100% of the time"
(A) Then
  one "can't be assured that a subsystem is going to work 100% of the time".
  
But respectfully, I don't agree with your original statement. As the example of 
redundancy pointed out, I can have a system (e.g., a RAID box) and be assured 
that a component *will* fail at some point, yet redundancy allows the 
containing system to work "100%" of the time. In other words, I can have 
components of known finite lifetimes in a system, yet the system has greater 
reliability than the best of its parts.