Re: On the usefulness of tables definitions in RM...

Cimode wrote:

>I lately came to the conclusion that teaching relation structures and
>manipulations by using tables inherently induces a bias to think of
>relations as relation values as opposed to relation variables.

The standard terminology is here:

  http://en.wikipedia.org/wiki/First-order_logic#First-order_structures

It uses 'relation' and 'structure',
but not 'relation variable' or 'table'.

>However, I believe that tables are elements of the presentation layer
>since they are only *one* possible representation in time of a
>specific relation.

In database theory, the term 'table' is usually reserved for what Codd apparently calls 'array': a two-dimensional array in which the relation's tuples are the rows and the columns represent attributes in a particular order. So the main difference between a table and a relation is that a table is ordered both horizontally and vertically.

>I am curious on whether this confuses more than it helps as far as
>operation definitions are concerned. What representations are to be
>preferred to avoid confusions ? In what context ?

If I were to teach, given enough time, I'd use mathematical logic to explain the principles, and terms like 'table' to refer to SQL databases, and explain the connection and differences.

-- 
Reinier