At 12:25 +0200 98/10/23, Jan Laitenberger wrote:
>[It] would destroy equational reasoning! For example you
>would be able to define different equalties on the same data
>structure.
It is in fact often useful to have more than one relation on data structures:
For example, even if one data structure is just partially ordered, it is
useful defining an additional total order which can be used to store the
elements on a tree. And two aliases (references) could be considered equal
when either they point at the same data or when the data they point at are
equal; either variation will be useful depending on the context.
Some thinking could probably define some widely used relations, like
"equal" and "indentical" in the case of aliases. But one can still not
ensure that this will suffice for every data structure.
Hans Aberg
* Email: Hans Aberg <mailto:[EMAIL PROTECTED]>
* Home Page: <http://www.matematik.su.se/~haberg/>
* AMS member listing: <http://www.ams.org/cml/>
