On 14/11/2011 9:36 AM, Patrik Eklund wrote:
Dear Vaughan,
An excellent remark, once again from your side.
The general audience of this remark may, however, not identify the subtlety of these states with respect to modelling of parallel programs and what apparently now happens on clouds and grids with services and brokers, and not even to mention customers using these services.
So perhaps I may suggest to recall e.g. the dining philosophers paradigm, which was widely used during the early days of CSP (Communicating Sequential Processes) decades ago. The philosophers go through only three states, namely, thinking, getting hungry (and thereby stop thinking), and eating. After eating then go back to thinking, and so on. They use chopsticks, one by one (in a very non-Asian fashion), and communicate about using these resources with fellow philosophers around the table. Simple objectives are e.g. to avoid starvation.
My recollection was that there were two versions - "dining philosophers" who had shared access to two forks, either one of which sufficed; and "dining Chinese philosophers" who had shared access to two chopsticks of which both were needed. But perhaps I have got it wrong? Robert [For admin and other information see: http://www.mta.ca/~cat-dist/ ]