Re: On Formal IS-A definition

On May 9, 2:34 am, Nilone <rea..._at_gmail.com> wrote:
> On May 8, 7:11 am, David BL <davi..._at_iinet.net.au> wrote:
>
> > Values are immutable. Variables accessed by imperative programs are
> > usually mutable. Sets are values. If a set contained a variable then
> > it wouldn't be immutable.
>
> We can generalize values and variables to elements of domains, where a
> value is any element of a domain while a variable is an element of a
> domain for which a homomorphism to another domain is defined.
> Assigning to a variable would reduce to modification of the
> homomorphism, so sets containing variables would not be modified by
> assignment to a variable.

Wrong. You can't modify a homomorphism just like you can't modify a number or a set. Homomorphisms are values and are therefore immutable. You have invented a homomorphism variable to hold a homomorphism value. What you claimed were variables were just values intended to act as inputs to a homomorphism function. Received on Sun May 09 2010 - 03:44:37 CEST