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From: "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>
Newsgroups: comp.lang.ada
Subject: Re: Languages don't  matter.  A mathematical refutation
Date: Sat, 4 Apr 2015 13:16:57 +0200
Organization: cbb software GmbH
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Date: 2015-04-04T13:16:57+02:00
List-Id: <comp.lang.ada>

On Sat, 4 Apr 2015 03:02:52 -0700 (PDT), jm.tarrasa@gmail.com wrote:

> El jueves, 2 de abril de 2015, 18:41:18 (UTC+2), Dmitry A. Kazakov  escribió:
>> On Thu, 2 Apr 2015 07:48:45 -0700 (PDT), j_...@gmail.com wrote:
> 
>> You must start with showing that "severity", "frequency" etc are random
>> variables. There is a clear definition of what a random variable is. It is
>> a measurable function from the set of elementary outcomes. The first step
>> is presenting the set.
> 
> What's the problem with severity and frequency?
> 
> They are measurable. 
> 
> Program "A" in a two-years period
> had bug1 which crashed program one time per day, and took a week to fix it
> had bug2 which destroyed data, one per month, and took two days to fix it
> had bug3 which was annoying, three per day, and took a month to fix it
> 
> Program "B" in a two-years period
> had bug1 which crashed program one time per hour, and took a month to fix it
> had bug2 which destroyed data, one a month, and took a week to fix it

'Measurable' in the definition of random variable has little to do with
measurements, e.g. physical measurements. It means a that the sets returned
by the function (random variable is a function) are measurable:

   http://en.wikipedia.org/wiki/Measurable_function

BTW, program crash is certainly not a random variable in most cases. The
only case when crash would be random is when the input is random, e.g.

   program Random_Crash is
      X : Dice;
   begin
      X := Read_From_Hardware_Random_Generator;
      if X then
         Execute ("format C: /q");
      end if;
   end Random_Crash;

-- 
Regards,
Dmitry A. Kazakov
http://www.dmitry-kazakov.de