RE: [Axiom-developer] "has" and "with" (was curious algebra failure)

[Weiss, Juergen]

I found the old document about type equivalence in Scratchpad. It's:
A New Algebra System, May, 29 th 1984, James H Davenport. I have only
found a paper version. Maybe someone has an online version.

It states that:
1. Two named types are only equivalent if the names are the same.
2. Anonymous types are equivalent when stucturally equivalent
3. An anonymous type is never equivalent to a named type.

So following 1.

t1 == List Term
t2 == List Term
x : t1
y : t2
y := x      

is not supposed to work,

but following 2.

x : List Term
y : List Term
y := x    

is ok,

and following 3.

t == List Term
x : List Term
y : t
y := x   

is not supposed to work as well

All examples are taken from the paper.

I am not sure how much of this design is preserved in the current
system. But without having had an intense look at the examples,
I got the impression, that they follow the rules above.

Regards

Juergen Weiss

Juergen Weiss     | Universitaet Mainz, Zentrum fuer Datenverarbeitung,
address@hidden| 55099 Mainz, Tel: +49(6131)39-26361, FAX:
+49(6131)39-26407
 

> -----Original Message-----
> From: address@hidden 
> [mailto:address@hidden
>  On Behalf Of Gabriel Dos Reis
> Sent: Monday, August 13, 2007 12:16 AM
> To: Bill Page
> Cc: address@hidden
> Subject: Re: [Axiom-developer] "has" and "with" (was curious 
> algebra failure)
> 
> On Sun, 12 Aug 2007, Bill Page wrote:
> 
> | On 8/12/07, Gabriel Dos Reis wrote:
> | > On Sun, 12 Aug 2007, Bill Page wrote:
> | >
> | > | If you prefer, now that we have this page nearly 
> finished we could
> | > | rename it to remove the SandBox prefix, then all 
> subscribers would be
> | > | notified of any further changes.
> | >
> | > That would be great!
> | >
> | 
> | Ok, now please refer to the page:
> | 
> | http://wiki.axiom-developer.org/AnonymousCategories
> 
> Many thanks.
> 
> -- Gaby
> 
> 
> 
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