On Sun, 12 Aug 2007, Bill Page wrote: | On 8/12/07, Gabriel Dos Reis <[EMAIL PROTECTED]> wrote: | > On Sat, 11 Aug 2007, Bill Page wrote: | > | ... | > | Unnamed categories are just values of type Category. | > | > But, that is not what Axiom Book says, section 12.12, page 525: | > | > The part of a category to the right of a with is also regarded as | > a category -- an "anonymous category". [...] | > [ rewriting packages with named categories skipped ] | > There is no reason, however, to give this list of exports a name since no | > other domain of package exports it. In fact, it is rare for a package to | > export a named category. [...] | > | > This, to me, suggest that the semantics described and intended in the | > Axiom Book is that two unnamed categories always yields different categories | > irrespective of their bodies. | > | | You must be reading between the lines :-)
certainly, as there is no formal description of the semantics! :-) Anything we can do is to guess, to read between the lines. | since I certainly can not | deduce that two unnamed categories are always distinct from the | quotation. In fact the opposite. The discussion of exporting a named | category here is rather gratuitous unless you assume that there is a | better reason for exporting "anonymous" categories than simple | convenience. The reason why most packages export anonymous categories | is precisely because of how named categories are interpreted: | categories with different names but identical structure are considered | distinct. This is important because Axiom wants to associate these | *names* with mathematical properties. In many cases the name must | carry the proper mathematical interpretation irrespective of whether | or not the categories have the same structure. | | See the examples at: | | http://wiki.axiom-developer.org/SandBoxCategories Thanks. | But notice that these examples also illustrate what I think is an | error in the result of evaluating has for category-valued expressions | in Spad. How does the compiler behave when the error we are discussing is fixed? I'm trying Juergen's suggested fix, which has different semantics than that of Stephen. -- Gaby _______________________________________________ Axiom-developer mailing list Axiom-developer@nongnu.org http://lists.nongnu.org/mailman/listinfo/axiom-developer
