Re: Do Data Models Need to built on a Mathematical Concept?

Neo wrote:

>>>A graph is not equivalent to a binary relation.
>>>A graph is composed of binary relations.
>>
>>Read my lips : any graph can be interpreted as a binary relation, 
>>and any binary relation can be interpreted as a graph.

Yes, I do have a background including reading a few books on Graph Theory, Set Theory and Abstract Algebra, more advanced books on Database theory, and apparently a gorup of people made the mistake to grant me a University diploma in Mathematics and Computer Science, which I know you don't have because no Math or CS graduate could debitate such non-sense.

You should visit your local public library more and you should follow at least some summer courses on basic CS topics.

A relation of degree n over the sets A1, A2, ..., An is simply any subset of the cartesian product A1xA2...xAn.

For a binary relation the notation is usually R <included in> AxB where we call A the domain of R and B the codomain of R. So we say R is a binary relation from A to B. When A and B (the domain and codomain coincide) we call that a *binary relation over A*. So a binary relation R over A is simply a subset of the cartesian product AxA.

Further more, given a binary relation R over A, A is implied in the definition of R (otherwise R is not defined), so all is left for you to do is put them together in the pair (A, R) and you got your directed graph.

For what a graph is I hope you do go and educate yourself, or maybe find another charitable soul on usenet, to explain to you what a graph is. Received on Sun May 04 2003 - 04:21:43 CEST