In the automatic train control system at our transit agency, we use something called a "Checked Redundant" processor that handles all the safety critical functions.
The architecture of the processor resembles three PLCs which are cross checked so all three must arrive at the same decision to activate some external device (like operating track switches or issuing a "permissive" speed code to the trains).
However the manual refers to an algorithm called "Polynomial Division" to evaluate the Boolean expressions representing all the variables which are used to determine the final decision.
So what exactly is a Boolean Polynomial and what is polynomial division?
The architecture of the processor resembles three PLCs which are cross checked so all three must arrive at the same decision to activate some external device (like operating track switches or issuing a "permissive" speed code to the trains).
However the manual refers to an algorithm called "Polynomial Division" to evaluate the Boolean expressions representing all the variables which are used to determine the final decision.
So what exactly is a Boolean Polynomial and what is polynomial division?