Re: Value

On Feb 23, 9:49 pm, r..._at_zedat.fu-berlin.de (Stefan Ram) wrote:
> r..._at_zedat.fu-berlin.de (Stefan Ram) writes:
> >A value in mathematics or computer science is any object or
> >entity.
>
> This notion is so wide that it might help to explain,
> what is /not/ a value.
>
> A simple model for this is the common mathematical
> language of terms and formulas.
>
> Usually, a term is not a value, a formula is not a
> value and the meaning of a formula is not a value.
> (In metamathematics, terms and formulas might become
> values, but usually they are not.)
>
> What is a value, is the meaning of a term.
> A term refers to a value, it denotes a value.
>
> In a simple procedural programming language, there
> are »expressions« and »statements« instead of
> »terms« and »formulas«. There, a value is what is
> denoted by a (non-void) expression.
>
> However, one must be careful, when defining a value
> as »what an expression denotes«, because this might
> create a circular definition, when an expression is
> being defined as a means to denote a value. Therefore,
> I have chosen to give a definition independent of
> expressions in my preceding post.
>
> In mathematical logic, a formula uses a relation symbol to
> assert a relation between certain entities. These entities
> are the values.

Surely this doesn't make any sense Stefan - a value cannot be an object in OO, because objects can change, whereas a value obviously cannot. Similarly it is generally when we refer to entities in the real world we can accept they can change, so again not values. This, yet again, all seems a bit symptomatic of the lack of definitions in OO, nevermind just theoretical underpinnings.

> So, anything than can have a relation
> to something else is a value. Therefore, I said, that
> a value is what one can make an assertion about.
Received on Sun Feb 24 2008 - 02:15:15 CET